Ultimate analysis based mathematical models are the most reported with Dulong's equation being among the first available to calculate the calorific value of coal or biomass. The higher heating value (HHV) at constant pressure measures the enthalpy change of combustion with water condensed. The HHVs (MJ/kg) of the lignocellulosic fuels as a function of carbon (C) or carbon + hydrogen (C + H) contents (wt%) were calculated using the following equations: [Formula: see text] [Formula: see text] for Equations (1 and 2) which in square of the correlation coefficients (r 2 ) were 0.9734 and 0.9814, respectively. There is a highly significant correlation between the HHV of the lignocellulosic fuels and their carbon or (carbon + hydrogen) contents.