Films of composites of tin oxide (SnO2) and carbon powder derived from waste banana peels were fabricated using the doctor blade method. Variation of the properties of films was measured for different weight compositions of SnO2 and carbon from 0% to 14% of carbon. The structural and optical properties of the samples were measured using X-ray diffraction (XRD) patterns and UV-visible spectrums. According XRD patterns, the structure of composites was similar to the structure of pure tin oxide by implying that the addition of carbon does not alter the structure. The crystallite size increased with the addition of carbon. The optical band gap gradually decreased with the increase of carbon percentage from 3.2612 to 2.1700 eV. The gas sensitivity of all the samples was measured at 1000 ppm of acetone at room temperature. The voltage across the sample decreased after adsorbing acetone. The highest gas sensitivity was observed for the sample with 90% SnO2 and10% Carbon. The gas sensitivity of the samples first increased with carbon percentage up to 10% of carbon, and then the gas sensitivity gradually decreased with the carbon percentage. Response time of all the samples with different compositions was higher than 100 min, although all the samples recovered faster. The response time gradually increased with the carbon percentage. Only a slight variation of recovery time was observed with the variation of carbon percentage.