The fourth order Runge-Kutta approximation was used to determine the substrate inhibition kinetics of Klebsiella sp. utilizing thiocyanate in batch culture. The hypothetical maximum growth rate, half saturation-, microbial yield-, biomass decay rate-, and substrate inhibition-coefficients were evaluated as being 0.62 +/- 0.05 day(-1), 85 +/- 8 mg SCN l(-1), 0.076 +/- 0.011 mg dry cell weight mg(-1) SCN, 0.03 +/- 0.002 day(-1), and 131 +/- 22 mg SCN l(-1), respectively. The apparent maximum specific growth rate and maximal substrate concentration resulting in apparent maximum growth rate were calculated to be 0.24 +/- 0.01 day(-1) and 106 +/- 9 mg SCN l(-1), respectively. (C) 2004 Elsevier Ltd. All rights reserved.