Gas sensing properties of P-N contact ceramics, composed of ZnO and CuO pairs sintered at different temperatures, were studied for 1% CO gas. Between 10$0^{circ}C$ and 32$0^{circ}C$ temperature range, it was observed that 2-probe current-voltage (I-V) characteristics, temperature and voltage dependence of sensivities were dependant largely upon ZnO samples. Pairs including a ZnO sample sintered at 110$0^{circ}C$ showed maximum senitivity of 9 and 13 depending upon counterpart CuO samples, at 260~29$0^{circ}C$. On the other hand, pairs including a ZnO samples sintered at 90$0^{circ}C$ showed increasing sensitivity within in the measured temperature range and maximum sensitivities were about 4.