In order to reduce the emission of NO_x, SO_x, and CO₂ and mitigate the dependence on the fossil fuel, the use of renewable energy, especially the biomass energy, has been explored. Since most biomass fuels are hard to grind to the very fine size, gasification is the preferred technology of energy conversion. Updraft fixed bed gasification using partial oxidation process is adopted where air less than the stoichiometric quantity is admitted to oxidize the char to CO. The temperature profile within the bed reveals a characteristic temperature peak. The results reveal a correlation between the higher heating value (HHV) of producer gas and the peak gasification temperature (T_peak). Coal with higher char content (~45%) is blended with biomass of low char content (~20%) in order to produce high quality gas. In this study, the Texas-based mesquite fuel was blended with Wyoming Power River Basin (PRB) coal with mass ratios of 100:0, 90:10, and 80:20 and fired downward into the gasifier. It was found that at a given mesquite to the coal mass ratio, the peak gasification temperature decreased with the increase in ER. With the increase of the coal ratio in the mesquite: coal blend and the peak temperature increased significantly; more combustible gases such as CO, CH₄ were generated at the end of product gas, and the HHV of the product gas increased by 10%-20%.