With the gradual depletion of coal and petroleum resources, biomass is being perceived as arnself-sustainable source of energy production. It is cheap and readily available as well.rnGasification is one of the potential sources for production of clean and eco-friendly fuel.rnASPEN PLUS simulator is a strong tool for investigating the behavior of a process and it canrnbe readily used to access various aspects like feasibility of an operation, effect of operatingrnparameters on the performance of a gasifier. In this paper, steady state simulation model ofrnair gasification has been developed in Aspen plus for fixed bed biomass gasifier using ricernhusk, coffee husk and saw dust as a fuel and the analysis of fuel samples was done throughrnultimate and proximate properties of the biomass. Aspen plus is selected as a simulation toolrndue to its higher capability of handling solid feed using physical models. The fixed bedrngasifier used here is an updraft type one with drying, Pyrolysis, gasification, and combustionrnstages. The gasifier has been modeled based on thermodynamic equilibrium model by Gibbsrnfree energy minimization in four stages. In the first stage moisture content of biomass feed isrnreduce through drying. In the second stage biomass is decomposed into its elements byrnspecifying yield distribution. In the third and fourth stages gasification and combustionrnreactions has been modeled using Gibbs free energy minimization approach. Simulationrnresult include; sensitivity analysis of Air to fuel ratio, gasification temperature, gasificationrnpressure, and, steam to biomass ratio have been varied over wide range and the effect ofrnthese parameters on syngas composition and lower heating value has been investigated. Thernsensitivity analysis results indicated that increase in air to fuel ratio decreases the heatingrnvalue of the producer gas. Temperature increases the production of CO and H2 and enhancesrnthe heating value of the producer gas. Higher pressure reduces H2 rich syngas hencerndecreases the lower heating value of the producer gases. Steam as a gasifying agent favorsrnhydrogen production which results in increase of hydrogen content in the syngas, whilernincrease of the steam to biomass ratio had negative effects on lower heating value of syngas.rnBased on the simulation results, maximum lower heating value of syngas was found at therngasification temperature of 800ÂºC, steam flow rate of 0.3 kg/hr, and pressure of 1bar wasrnobtained at air flow rate of 0.5 kg/hr for 1.5 kg/hr of each feed stocks.