With p-chloroaniline (PCA) as a selected substrate, the mixed microorganisms assimilating it as the sole source of carbon and nitrogen were obtained by acclimation technique from the enriched cultural products of degraded p-dichlorobenzen (p-DCB). The mixed microorganisms immobilized in a packed-bed reactor were used to degrade PCA. In the packed-bed bioreactor, the biodegradation of PCA followed the Logistic equation, q = qmax/(1+ealpha-betaUv). The major kinetic parameters, Ks (half velocity constant) and qmax (maximum specific substrate degradation rate), were calculated. PCA was found to be degraded with a concomitant release of chloride ions into the substrate. Under -the conditions of residence time of 3 hours and inlet stream at PCA concentration of 360 mgcntdotL-1, the volumetric degradation rate of the substrate was 125 mgcntdotL-1cntdoth-1, with removal efficiency of 91%.