To explore a new method of determing enzyme activities,and reduce the disturbing factors' effects on this determination,and raise the accuracy of enzyme determination,low electropotential meter and thermocouple are used to determine catalase activities. While the concentration of H 2O 2 is 9.6%,the enzyme activities from 0.5 u to 3.5 u can be detected;while H 2O 2 concentration from 2.4% to 7.2% ,the enzyme reaction velocity is in direct proportion to substrate concentration. Above 9.6% substrate concentration,the velocity of the en...