Co and Ni as catalysts in SnO2 sensors to improve the sensitivity for CH4 gas and CH3CH2CH3 gas were coated by a solution reduction method. SnO2 thick films were prepared by a screen-printing method onto Al2O3 substrates with an electrode. The sensing characteristics were investigated by measuring the electrical resistance of each sensor in a chamber. The structural properties of SnO2 with a rutile structure investigated by XRD showed a (110) dominant SnO2 peak. The particle size of the SnO2:Ni powders with Ni at 6 wt% was about 0.1 μm. The SnO2 particles were found to contain many pores according to a SEM analysis. The sensitivity of SnO2-based sensors was measured for 5 ppm of CH4 gas and CH3CH2CH3 gas at room temperature by comparing the resistance in air to that in the target gases. The results showed that the best sensitivity of SnO2:Ni and SnO2:Co sensors for CH4 gas and CH3CH2CH3 gas at room temperature was observed in SnO2:Ni sensors coated with 6 wt% Ni. The SnO2:Ni gas sensors showed good selectivity to CH4 gas. The response time and recovery time of the SnO2:Ni gas sensors for the CH4 and CH3CH2CH3 gases were 20 seconds and 9 seconds, respectively.