Fungal cultivation in a biological real-time reaction calorimeter (BioRTCal) is arduous due to the heterogeneous nature of the system and difficulty in optimizing the process variables. The aim of this investigation is to monitor the growth of fungi Aspergillus tamarii MTCC 5152 in a calorimeter. Experiments carried out with a spore concentration of 10(5) spores/mL indicate that the growth based on biomass and heat generation profiles was comparable to those obtained hitherto. Heat yield due to biomass growth, substrate uptake, and oxygen uptake rate was estimated from calorimetric experiments. The results would be useful in fermenter design and scale-up. Heat of combustion of fungal biomass was determined experimentally and compared to the four models reported so far. The substrate concentration had significant effects on pellet formation with variation in pellet porosity and apparent density. Metabolic heat generation is an online process variable portraying the instantaneous activity of monitoring fungal growth and BioRTCal is employed to measure the exothermic heat in a noninvasive way.