A fourth order Runge-Kutta approximation was used to determine the Monod kinetics of Candida rugopelliculosa by using unsteady state data from only one continuous unsteady state operation at a fixed dilution rate. The maximum microbial growth rates, mumax, and half saturation coefficient, K-s, were 0.82 +/- 0.22 h(-1) and 690 +/- 220 mg soluble chemical oxygen demand (SCOD) l(-1), respectively. The microbial yield coefficient, Y, and microbial decay rate coefficient, k(d), were 1.39 +/- 0.22 x 10(4) cells mg(-1) SCOD and 0.06 +/- 0.01 h(-1), respectively.