The aim of the biomass gasification process is syngas production. It is a complicated chemical process during which fuel goes through pyrolysis, oxidation and reduction stages. Syngas composition and process behaviour depends on many different factors. Gasifier design, fuel properties and gasifier operation settings have dominant influence. This study presents a model to simulate the gasification process and describe biofuel moisture effect on process efficiency. Biomass torrefaction possibilities before gasification process were investigated. Acquired heat from the syngas cooling was used for torrefaction process in the model. Results show that the total efficiency of the gasification process can be increased using biomass torrefaction. However, there is some critical point of fuel moisture content when application of torrefaction process is reasonable.