Carbon Capture and Storage Technology (abbr. CCS) is recognized as one of the most successful method in climate changes mitigation. Depleted hydrocarbon reservoirs represent a realistic option for its application. The subject of research are Neogene (Upper Miocene) sandstone hydrocarbon reservoirs in the Sava Depression, represented by the Ivanić Field case study. Teoretical storage capacity for some aquifers and hydrocarbon reservoirs in the Republic of Croatia has been assesed on 188.83·106 t within the 6th Framework Programme projects (FP6), CASTOR and GeoCapacity. Calculation was made by using a simplified methodology based on data on ultimate recoverably reserves. The storage capacity for the Ivanić Field is assessed on 5.4λ6·106 t. For more accurate assessment distribution of petrophysical parameters must be done, which is possible by using different geostatistical, deterministic and stochastic, assessment methods. Within the scope of dissertation, variogram analysis and mapping of the Ivanić field's reservoir variables were done. Calculated volume of CO2 which can be injected after the Enhanced Oil Recovery (EOR) project, up to conditions of initial reservoir pressure, is on the level of 13.722·106 t. It was also simulated using material balance equation for produced and injected fluid in the MBAL program module. Obtained value (3.705·106 t) is of the practical capacity level. CO2 geologic storage system must allow permanent and safe disposal of CO2 (of the order of 104-105 years). Although migration of CO2 through active and abandoned wells, fractures and faults is a real possibility, these issues are well investigated so far, such attention has not been paid to reservoir seal rocks migration pathway. Probability of preserving reservoirs saturated by CO2 is done by applying the probability of successful discovery methodology (Probability of Success, abbr. POS). By testing seal rocks permeability the hypothesis of the need for laboratory tests was justified and for that purpose, in the scope of dissertation, an innovation „Chambers for testing of isolator rocks impermeability for carbondioxide accumulated in reservoir below seal" was designed, which was awarded with a silver medal at the International exhibition of innovation and modernization, INOVA 2013. Temporary, the patent is under verification of the satate authority institution. Mineral trapping mechanism is the safest mechanism for permanent CO2 retention, but due to long process, this phenomenon is still quite unexplored. Possibility of mineral trapping for the Sava Depression’s hydrocarbon reservoirs is done by analogy with published data of other projects. Sandstones composed of quartz, dolomite and K-feldspar, as it is case in the target sandstones may be considered favorable for mineralization, but there is no significant CO2 binding capacity due to lack of alkaline earth metals (Ca and Mg) and/or mafic rocks fragments. Given that some clay minerals, (such as anorthite, zeolite, smectite, etc) are considered reactive, mineralisation may occur in transitional lithofacies. Accurate assessment could be obtained after many years of research in controlled laboratory conditions. In CO2 geological storage the temperature represents an important factor because it significantly affects fluid physical properties, interaction of the CO2-reservoir fluid-rock system, the trapping mechanisms, and the storage safety. For the effective CO2 storage pressure and temperature must be above supercritical. However, VILARRASA et al. (2013) analysed changes in stress caused by injecting cold CO2, and concluded that injection of liquid CO2 is more favorable regarding energy efficiency and seal rock mechanical stability. The changes in fluid pressure and temperature can lead to gas phase appearance causing different problems. Modelling of CO2 pipeline transportation was done in a specialized software (HYSYS) by using a part of exsisting pipeline system. The transportation conditions were carefully selected to achieve a balance between transport safety, storage efficiency and migration risk reduction. The values of the inlet temperature (40 ° C, 65 ° C and 80 ° C) and inlet pressure (140 bar, 180 bar and 200 bar) were carefully chosen to meet criteria of pipeline transportation in supercritical state and its injection into the reservoir in liquid state. Simulation results showed that for the fluid phase preservation, a sufficient supply is needed because, due to the pipeline lenght, the heat transfer coefficient significantly influences the change in phase equilibria. Preservation of supercritical fluid flow requires huge energy demand for heating, putting into question project's viability. In order to maintain fluid temperature through the selected pipeline system, mass flow should be greater than 20 000 kg/ h. Regarding power consumption, temperature of 40 ° C and pressure of 140 bar was selected as most suitable. As depositional environment, structure and Neogene lithofacies in the Ivanić Field completely fit into the geological history of Croatian Pannonian Basin System evolution or into individual structures in that area, the model of CO2 injection and storage made in this dissertation can be considered applicable throughout the whole area.