Many pharmaceuticals and personal care products have been detected as aquatic pollutants all over the world. The class of compounds, known as the nitrofuran antibiotics (furaltadone, furazolidone, nitrofurantoin (NFT)) are expected to be found in environment based on their big production and use. Due to increasing presence in aquatic systems, application of advanced oxidation processes play important role in removal of pharmaceuticals from wastewaters. In this work, the aquatic photochemical degradation of nitrofurantoin was investigated by application of direct photolysis as well as photocatalytic oxidation with TiO2 in the UV/Vis range. Photochemical experiments were carried out in laboratory-scale reactor with external light source. The heterogeneous reaction mixture, TiO2 suspension was circulated by continuously bubbling oxygen or argon within the reactor. Degradation of antibiotic was investigated by high-performance liquid chromatography and spectrometry. The effects of the irradiation wavelengths and the presence of oxygen and argon were also studied in the case of direct photolysis. Spectral and chromatographic results clearly indicated that in direct photolysis the starting antibiotic compound underwent structural transformations strongly deviating from the reactions in the case of TiO2-mediated photocatalysis. The fast, first step of the direct photolysis is attributed to photoisometization around the C-N double bond, followed by a slow second step of the photodegradation. Heterogenous photocatalytic degradation of nitrofurantoin was much more faster than photolytic degradation accompanied by a considerable decrease of pH. The key degradation product of photolytic and photocatalytic degradation of nitrofurantoin was identified by application of mass spectrometry.