since holocellulose constitutes a major portion of a number of biomass sources, research and development for its conversion to high grade fuel is of considerable interest. however, realization of conceptual and laboratory proposals and their practical merit, will depend on the fuel input requirements of the total required engineering system. these fuel requirements must include those of all mechanical and chemical mainpulations and operations.there are no direct relations between hhv and the holocellulose of the lignocellulosic fuel, but there are good relations between the lignin contents and the determined hhvs of the lignocellulosic fuel samples. thus, the hhvs of the renewable natural fules can be calculatedby using the lignin content obtained from simple chemical analysis. the experimental determination of hhv require special instumentation, whereas chemical analysis data can be obtained relatively easily by avilable laboratory equipment.mathematical equations have been developed to calculated the hhvs of various lignocellulosic fuel from their chemical analysis data. the calculated hhvs using these new correlations show mean differences from the measured values ranging from 0.07 to 0.26 %. result obtained from eqs 2- 4 developed in this work show excellent agreement with experimental results for the used samples