Production and consumption of pharmaceuticals increase and because of that their concentration in the environment is also getting bigger. Under the influence of different environmental factors and depending on physico-chemical properties of pharamceuticals; pharmaceuticals degrade. Toxic products can arise during degradation of pharmaceuticals so it is very important to examine their degradation. The aim of this work was to examine abiotic processes, hydrolytic and photolytic degradation, of hydroxychloroquine. The rate of hydrolytic and photolytic degradation was monitored by high performance liquid chromatography with diode array detection (HPLC-DAD). Hydrolytic degradation of hydroxychloroquine was performed in ultra-pure water at three pH-values (4, 7 and 9) and it was noticed that hydroxychloroquine did not hydrolyze. Photolytic degradation was performed in ultra-pure and spring water and it was noticed that degradation was faster in spring water. Furthermore, the impact of pH-values on photolytic degradation was monitored in two ways: (i) in buffer solutions that resist change of pH-values and (ii) in solutions with a preset pH-values (4, 7, 9 and 10) because during degradation pH-values change. By increasing the pH-value, the rate of degradation was increased and half-life time decreased. During degradation of hydroxychloroquine, formation of two degradation products were observed.