Abstract Metabolic heat responses during Carboxypeptidase Y production by Kluyveromyces marxianus was estimated by optimizing the aeration and agitation rates. 1 LPM and 150 RPM was found to be optimum for maximum Carboxypeptidase Y production in a 2L capacity bioreaction calorimeter. The effect of pH on Carboxypeptidase Y production was carried out extensively in this study. Under controlled pH conditions, Kluyveromyces marxianus utilized both the substrate (glucose) and the by-product (ethanol) effectively to yield a maximum of 19 IU/mL compared to 10 IU/mL Carboxypeptidase Y under uncontrolled pH conditions. Biokinetic constants, Oxygen Mass Transfer coefficient, Shear stress and total metabolic heat of the reaction were estimated. For the first time, biocalorimetric coupled respirometric studies have given a maximum Carboxypeptidase Y yield making it attractive for commercial applications.