An experimental investigation on the gasification of corncobs was conducted in an 18 kW pilot-scale fixed bed system for power generation. The main objective was to determine the effect of gasifying corncob mixtures with fines content (particle size below 10 mm) on the performance of the system. To achieve the objective, a 2× 3 factorial arrangement was developed. The analysis considered three resistive loads connected to the generator (4, 8, and 12 kW) and two different size ranges of biomass (one with 100% of chips within the actual recommended size (10–40 mm)) and the other with a content of 15% of fine particles (particle size below 10 mm). An increase of 15% in fine material content in the feedstock and a stable electricity demand close to the rated capacity, significantly increased the temperature of the process and decreased the mean specific fuel consumption – SFC (2.06 kg/kWh at 67% of rated capacity). H2 and CO production increased by increasing reactor temperature, reaching concentrations of 16.7% and 17% respectively at the higher resistive load (12 kW). Cold gas efficiency varied in the range of 33.7%–37.0%, increasing slightly with the blend of fines content and higher applied load.