A method for measuring cellobiase activity of theTrichoderma reeseiCCF 1853 cellulase complex using a Thermal Activity Monitor and a flow - mix mode is described. The kinetic constant KMand the linear dependence of dQmax/dt (the maximum heat flow at the total saturation of enzyme with substrate) on the enzyme concentration were determined. The process of the end product inhibition of cellobiase activity by glucose has been observed too. The obtained results allow to determine the mechanism of the inhibition and an inhibition constant for glucose.