Cyanide is a well-known constituent of mine wastewater which can be degraded by various process. However, due to cost and environmental challenges, microbial degradation seems to be the most effective process. When wastewater is treated with microorganisms, process performance should not only be based on toxicant degraded but also on the impact of the toxicant on the physical properties of the microorganisms. Heat capacity of lyophilised biomass of Fusarium oxysporum was measured using modulated differential scanning calorimeter. The heat capacity for F. oxysporum grown in cyanidation wastewater was 1.1982, 1.077 and 1.143 J K-1 g-1 on glucose (GA), Beta vulgaris (BA) and cyanide supplemented with Beta vulgaris (BCN), respectively at 298.15 K and 1 atm. The enthalpy of formation of dry biomass are -297.58, -233.07 and -278.60 kJ/C-mol for BA, BCN and GA, respectively. These values were found to be within the range of some biological molecules. The presence of cyanide in the wastewater minimally affected the thermodynamic property of the dried biomass of F. oxysporum.