In this Thesis, systematic research of spontaneous precipitation of calcium oxalate at three different complexities (simple, NaCl and artificial urine system) and two initial pH (pHi = 5.0 and 9.0) was conducted. In all investigated systems, dominant precipitation of calcium oxalate monohydrate (COM) was observed, except in artificial urine system at pHi = 9.0, ci(C2O42-) ≥ 6.0 mmol dm-3 and ci(Ca2+) ≥ 7.5 mmol dm-3 where precipitation of a mixture of calcium oxalate monohydrate (COM) and calcium oxalate dihydrate (COD) occured. The influence of seven amino acids (nonpolar - Ala, Phe; polar - Gly, Ser, Cys and charged - His, Asp) on spontaneous pecipitation of calcium oxalate in hyperoxaluria conditions (ci(Ca2+) = 7.5 mmol dm-3 and ci(C2O42-) = 6.0 mmol dm-3) was studied in order to elucidate their role in precipitation of calcium oxalate hydrate. In all three investigated systems, significant influence of studied amino acids on morphology and crystal growth of COM was noted. The changes were more pronounced at pHi = 9.0. Only in the artificial urine system at pHi = 9.0, the change in composition was observed, polar aminoacids and nonpolar Phe inhibit precipitation of COM. In this Thesis, COD was synthesized for the first time with ultrasonic mixing. Crystal seed of COD in a shape of proper tetragonal bipramids with prism was prepared in ultrasonically mixed system: ci(Ca2+) = 9.00 mmol dm-3, ci(C2O42-) = 2.33 mmol dm-3 and c(citrate) = 9.00 mmol dm-3 (ci(Ca2+)/ci(C2O42-) = 3.86). It was observed that the ci(Ca2+)/ ci(C2O42-) ratio, c(citrate) and the way of mixing singnificantlly influenced morphology of COD crystals.