Soil dehydrogenase plays a role in the biological oxidation of soil organic matter and can be considered a good measure of the change of microbial oxidative activity under environmental pollutions. However, the kinetic characteristic of soil dehydrogenase under heavy metal stresses has not been investigated thoroughly. In this study, we characterized the kinetic characteristic of soil dehydrogenase in 14 soil types, and investigated how kinetic parameters changed under spiked with different concentrations of cadmium (Cd). The results showed that the K-m and V-max values of soil dehydrogenase was along 1.4-7.3 mM and 15.9-235.2 mu M h(-1) in uncontaminated soils, respectively. In latosolic red soil and brown soil, the inhibitory kinetic mechanism of Cd to soil dehydrogenase was anticompetitive inhibition with inhibition constants (Ki) of 12 and 4.7 mM, respectively; in other soils belonged to linear mixed inhibition, the values of K, were between 0.7-4.2 mM. Soil total organic carbon and Ki were the major factors affecting the toxicity of Cd to dehydrogenase activity. In addition, the velocity constant (k) was more sensitive to Cd contamination compared to V-max and K-m, which was established as an early indicator of gross changes in soil microbial oxidative activity caused by Cd contamination. (C) 2017 Elsevier B.V. All rights reserved.