In this study, three different precipitation systems of increasing complexities were used to study formation of calcium oxalate hydrates under hyperoxaluria conditions. For this purpose, three different precipitation systems have been studied: (a) a simple system (a system containing constituent ions), (b) NaCl system (a system consisted of constituent ions and 0.3 mol dm −3 NaCl), and (c) artificial urine system (a system containing constituent ions that are of the type and quantity mimicking real urine) at initial pH (pH i  = 6.5) value, with and without added vitamin C. The vitamin C has been extensively tested for its ability to inhibit or promote the process of calcium oxalate precipitation or the formation of specific hydrate modification. In order to determine whether calcium oxalate crystallization could be affected by the presence of vitamin C in precipitation systems with increasing complexity, different amounts of vitamin C (in the mass range from 100 to 1000 mg) were added to the precipitation systems. The results indicated that in all investigated simple systems, calcium oxalate monohydrate (COM) is observed to be dominant precipitated hydrate phase, while in NaCl systems precipitation of COM and calcium oxalate trihydrate (COT) mixture occurrs, except in reference NaCl system (without addition of vitamin C) where COM precipitated exclusively. In reference artificial urine system, calcium oxalate dihydrate was observed to be dominant precipitated hydrate phase, while addition of vitamin C promoted precipitation of COT. Significant differences are mainly observed in crystal morphology and the content of individual hydrate phases. Electrochemical measurements have indicated the existence of electrostatic interactions between seed crystals and ascorbic acid, even at low masses of added vitamin C.