The effect of selected variables on pentachlorophenol (PCP) dechlorination and degradation by a PCP-mineralizing Pseudomonas sp. UG30 was studied. Maximum rates of PCP dechlorination and degradation increased linearly with increasing initial cell densities up to 1.1 x 10(9) CFU cm(-3) and then levelled off. Maximum rates of PCP dechlorination and degradation decreased as the initial PCP concentration increased. Degradation of 400 ppm PCP was incomplete and stopped when 120 ppm Cl- was released into the medium. It was found that Cl- ions inhibited PCP degradation at a concentration of 100 ppm and higher. Enzymes involved in PCP dechlorination and degradation by UG30 cells were inducible, but not repressed by glucose. UG30 cultures were able to degrade PCP at 10 degrees C and rates increased linearly with increasing temperature to 30 degrees C. Apparent activation energies for PCP dechlorination and degradation were 7.72 and 9.13 kcal mol(-1), respectively.