The degradation kinetics of orbifloxacin [1-cyclopropyl-5, 6, 8-trifluoro-1, 4-dihydro-7-(cis-3, 5-dimethyl-1-piperazinyl)-4-oxoquinoline-3-carboxylic acid] was investigated as a function of pH (1.5-10.5), temperature (100-120°C) and buffer concentration (0.05-0.2M) by means of high-performance liquid chromatography.The degradation of orbifloxacin in aqueous solution followed apparent first-order kinetics under all experimental conditions. No appreciable effect of buffer on the degradation of orbifloxacin was observed for any of the buffer species used in this study. The log k-pH profiles indicated specific-acid and specific-base catalyses and there were inflection points near pH 6 and 9 corresponding to the pK_a1 and pK_a2 values. From the Arrhenius plots, the activation energies for k'_H, k'_H2O, k_H2O, k''_H2O and k''_OHwere found to be 31.9, 36.9, 23.5, 26.5 and 19.0 kcal/mol, respectively. Arrhenius data obtained from this study showed that the degradation of orbifloxacin at room temperature negligible at all pH values studied conditions (pH 1.5-10.5).