Low-cost sensors based on CuS-CuO nanoparticles were fabricated in spray technology and were used as gas sensors for H2S and NH3. The devices had good responses to H2S and NH3 at room temperature. The sensor based on CuS prepared with H2S at 323 K and CuS to CuO molar ratio of 1:15 had the highest response value 3139 to 1.88% H(2)s at operating voltage 8 V. The sensor based on CuS prepared with H2S at room temperature and CuS to CuO molar ratio of 1:20 showed a good linear response to H2S gas from 0.85 to 4.25% at 2 V operating voltage. The sensor based on CuS prepared with H2S at room temperature and CuS to CuO molar ratio of 1:20 had the highest response value 218 to 9.88% NH3 at operating voltage 2 V. The linearity interval of the sensor response to NH3 gas was from 2.88 to 9.88% at 2 V operating voltage. No response to NO2, SO2, water vapor and organic solvent vapors was observed. The response and recovery times were satisfactory. Temperature and operating voltage significantly affected the response of the sensors to H2S and NH3. (C) 2013 Elsevier Ltd. All rights reserved.