In this work, the biodegradation of nonylphenol by Rhodotorula sp. in batch culture was investigated over a wide concentration range (11~160 mg/l). Experimentally nonylphenol was an inhibitory type substrate to Rhodotorula sp.. Five kinetic models (Haldane, Webb, Yano, Aiba, and Teissier) were fit for the experimental growth kinetic data. It was found that the Haldane model was the most suitable one to predict the degradation of nonylphenol. The kinetic analysis demonstrated that bacterial growth and nonylphenol degradation of Rhodotorula sp. were based on a substrate concentration inhibition model. Analysis of growth factors indicated the highest specific growth rate (μ) of 0.127 h-1 was obtained at the initial nonylphenol concentration of 12.76 mg/l.