Each cultivar or hybrid has different requirements according to environmental conditions and soil properties and requires certain specifics in the production technology. Despite the well known fact that rapeseed for high yields should have large amounts of nitrogen, which is the biggest input, there are little scientific researches into the available literature to study of nitrogen fertilization effect on the agronomic and energetic traits of the rapeseed. After rapeseed harvest there are a large quantity of stalks on field that can be used as raw material for biofuels production. In contrast to rapeseed, spelt requires significantly less nitrogen and produces a larger quantity of biomass (straw and glumes) compared to other cereals and is also suitable as raw materials for energy production. Optimization of nitrogen fertilization for all crops, including rapeseed and spelt, must balance the relationship between the yield and quality of feedstock whether it is a seed or grain or biomass, with concurrently protecting the environment. Consequently, the aim of this study was to determine the agronomic traits of rapeseed and spelt, with regard to the selection of cultivar and fertilization with different nitrogen rate and determine the energetic traits of biomass as a feedstock for production heat and/or electricity in the selection of culture, cultivar and different nitrogen fertilization. Research was carried out through laboratory and field experiments placed on anthropogenic, eutric brown soil in the environmental conditions of northwestern Croatia. Research was placed on the University of Zagreb, Faculty of Agriculture experimental field throught two growing seasons for each crop. In 2012/2013 and 2013/2014 year were researched three different genotypes of rapeseed (conventional hybrid SY Cassidy, cultivar Komando and semi-dwarf hybrid PR45D03) and three variants of nitrogen topdressing. In nitrogen topdressing variants were included soil mineral nitrogen supply. Variants of nitrogen topdressing was: N1 - without topdressing, N2 - a difference from nitrogen fertilizers to 150 kg ha-1 of nitrogen in the soil in one application and N3 - the difference of nitrogen fertilizer to 200 kg ha-1 of nitrogen in the soil applied in two topdressing (60 % in stage BBCH 30 + 40% at the stage BBCH 39). In 2012/2013 year soil mineral nitrogen supply was 77 kg ha-1 and in the first rapeseed topdressing was applied 73 kg ha-1 of nitrogen (N2), in the second topdressing another 50 kg ha-1 of nitrogen fertilizer, which has added a total 123 kg ha-1 of nitrogen (N3). In 2013/2014 year soil mineral nitrogen supply was 60 kg ha-1, therefore, in the first topdressing was applied 90 kg ha-1 of nitrogen fertilizer (N2), in the second topdressing another 50 kg ha-1, in which is applied a total of 140 kg ha-1 nitrogen fertilizer (N3). Rapeseed agronomic traits were included seed yield, oil content and oil yield, stalk yield, pod residues yield and harvest index. Spelt agronomic traits were included hulled and dehulled grain yield, content of glumes, glumes yield, straw yield and harvest index. In 2013/2014 and 2014/2015 year were investigated three spelt cultivars (Nirvana, Ostro and Bc Vigor) and three variants of nitrogen topdressing: N1 - without topdressing, N2 - 25 kg ha-1 of nitrogen in one application and N3 - 50 kg ha-1 of nitrogen in two applications, first 25 kg ha-1 N at the beginning of the growing season in spring and second 25 kg ha-1 N at the end of tillering. In laboratory investigation for both cultures were determined content of combustible substances (content of carbon, hydrogen, sulfur, oxygen and volatile matter) and noncombustible substances (content of ash, coke, fixed carbon, nitrogen and moisture). Also, in laboratory for both cultures were determined calorific value and calculated energy potential. In both years were determined significant differences between studied cultivars and hybrids of rapeseed in seed and oil yield. Significantly the highest seed yield and oil yield achieved a conventional hybrid SY Cassidy. In 2012/2013 year the highest yield of the stalk and empty pods achieved conventional hybrid SY Cassidy and cultivar Komado. Increasing a rate of nitrogen, i. e., the application of 90 kg ha-1 of nitrogen in one topdressing (N2) significantly increased seed yield, and by the application of 140 kg ha-1 of nitrogen in two topdressing (N3) increased the stalks yield and empty pods yield, but only in extremely humid 2013/2014 year. The investigated spelt cultivars were significantly different in dehulled grain yield and harvest index. Significantly highest yield of hulled grains and the highest harvest index was achieved the cultivar Nirvana. In 2014/2015 year the highest yield of straw was achieved cultivars Bc Vigor and Ostro, and the lowest proportion of glumes achieved cultivar Nirvana. By increasing rate of nitrogen, i.e., the application of 25 kg ha-1 of nitrogen in the first topdressing (N2) significantly increased straw yield only in humid 2013/2014 year and yield of dehulled and hulled spelt grain and glumes yield in 2014/2015 year. Results of laboratory researches have shown that spelt straw has a higher calorific value than rapeseed stalks because it contains a higher content of carbon, coke and fixed carbon and low content of oxygen, volatile matter and nitrogen. Spelt straw in relation to rapeseed stalk contains less sulfur content. The most favorable energetic traits of the rapeseed stalk had conventional hybrids SY Cassidy and cultivar Komando. Topdressing with larger nitrogen rate mostly had a positive effect on energetic traits of the biomass i.e. rapeseed stalk through increasing the proportion of hydrogen and coke and reducing content of volatile matter. Investigated spelt cultivars were not significantly different in quality straw biomass, only in 2014/2015 year significantly lowest ash content was determined for cultivar Nirvana. Nitrogen topdressing also had mostly positive effect on energetic traits of spelt straw through increasing carbon content and decreasing oxygen and ash content, but also had negatively effect due to decreasing coke content and increasing nitrogen content. The yield of usable biomass counted 30% of the rapeseed and spelt biomass that can pick up and drive away from the field without disturbing soil fertility and structure. In this research, spelt straw achieved a higher yield of usable biomass (2492 kg ha-1) and the energy yield of biomass (42455 MJ ha-1) in relation to the rapeseed stalks (2235 kg ha-1, or 37037 MJ ha-1). With regard to the Croatian energy potential, rapeseed had higher energy potential in relation to the spelt due to significantly larger harvested area. Thus, in Croatia, from harvested area under rapeseed in the studied period, was possible to use on average 764414 GJ of energy and from the area under the spelt 48529 GJ of energy. The amount of energy from rapeseed biomass corresponds to 18258 tons of crude oil equivalent and from spelt biomass corresponds to 1159 tons of crude oil equivalent. Rapeseed stalks and spelt straw have high C/N ratio. Cultivar/hybrid and nitrogen topdressing of rapeseed didn’t have significant influence on C/N ratio of rapeseed stalk. Also, these factors didn’t have significant influence on C/N ratio of spelt straw.