Struvite was pptd. from NH4H2PO4, MgCl2 center dot 6H(2)O, and B3+, Mn2+, Co2+ and Mo6+-ions-contg. aq. solns. to det. kinetic parameters of the continuous struvite reaction crystn. calcd. by using Rojkowski exponential size-dependent growth rate model. With the increase of B, Co and Mo ions concns., the d. of nuclei decreased advantageously but increased with the increase in Mn ion concn. Linear growth rate of the nuclei increased with B, Co and Mo ions concn. increase but decreased with the increase of Mn ion concn. The relatively stable and narrow range nucleation rates were obsd. (10(12)-10(13) 1/(s.m(3))) which was not affected by pH raise, elongation of residence time and redn. of phosphate(V) ions concn. in a feed stream of crystallizer. Good consistence of obtained struvite reaction crystallization kinetics of model mixts. with the real cattle liq. manure was obsd.