In order to investigate the effects of inoculum source and pre-incubation on methane production performance of chicken manure (CM) and corn stover (CS), two sets of bio-methane potential tests using non- and pre-incubated inocula (digested sludge from a municipal wastewater treatment plant (DSMW) and digested sludge from a chicken manure treatment plant (DSCM)) were conducted at 37 A degrees C. Modified Gompertz and first-order models were used to evaluate the kinetic parameters. The results revealed that DSMW was better than DSCM in digesting organic substrates (CM and CS), since the average ultimate methane yields were 351 mL g(-1) volatile solid (VS)(added) for CM and 300 mL g(-1) VSadded for CS when DSMW was used as inoculum, and 298 mL g(-1) VSadded for CM and 218 mL g(-1) VSadded for CS when DSCM was used as inoculum, respectively. Nevertheless, there was no significant difference (p > 0.05) in the ultimate methane yields between non- and pre-incubated inoculum for digesting CM and CS, regardless of the inoculum source. However, when evaluating the kinetic parameters of anaerobic digestion, the correlation coefficient, maximal methane production rate, and hydrolysis rate constant were slightly higher using pre-incubated inoculum as compared to non-incubated inoculum.