The present study reports the kinetics of p-nitrophenol (PNP) biodegradation by Arthrobacter chlorophenolicus A6 in batch shake flasks for initial PNP concentrations in the range of 25-225 mg l(-1). Results of batch growth kinetics of A. chlorophenolicus A6 at various initial PNP concentrations revealed that the culture followed substrate inhibition kinetics with estimated decay coefficient value of 0.0132 h(-1). Biokinetic constants involved in the process were estimated by fitting the experimental data to several substrate inhibition kinetics models available from the literature. Among the models tested, Webb model fitted the experimental data best with the least root mean square error value, and the estimated model constants values were mu = 0.161 h(-1), K (i) = 128 mg l(-1), K (s) = 60.15 mg l(-1), and K = 100 mg l(-1). In addition, observed and theoretical yield coefficients, maintenance energy, and specific growth rate of the culture at various initial PNP concentrations were also investigated in the study.