Inactivation of four species of foodborne pathogens (E. coli, Salmonella, E. faecalis, and S. aureus) was investigated during laboratory-scale composting of fresh cow manure with addition of calcium cyanamide (CaCN 2 ) at constant temperature conditions, and the effects of temperature and additive content of CaCN 2 on the efficacy of inactivation were evaluated. At different composting temperatures (20, 30, 37 and 50 8C), a significant inhibition or quick inactivation of pathogens were observed during 10 d composting with addition of 2.0% CaCN 2 , and the effect was more obvious at mesophilic temperatures compared to thermophilic temperature. Therefore, the ideal additive content of CaCN 2 was determined at 30 8C through mixing 2.0%, 2.5%, and 3.0% CaCN 2 with manure. With increase in additive content of CaCN 2 , the efficacies of pathogen inactivation also increased. However, the result indicates that, no less than 2.5% CaCN 2 should be mixed with the manure to entirely eliminate the pathogens during composting.