Temperature and CO2 are two important parameters related to climate change, which affect crop yield of a particular region. In this study, an attempt was made to assess the impact of these parameters on the productivity of wheat crop in Bihar. For this purpose CROPSIM-CERES-Wheat model 4.6 was used in which weather data of 1981-2010 was used as baseline to assess the change in wheat yield under different climate change scenarios for four locations viz. Pusa (zone I), Purnia (zone II), Sabour (zone III A) and Patna (zone III B) in Bihar. The model was run for the scenarios like 1o , 2o , 3o and 4 o C increase in mean temperature keeping all parameters normal. Similarly change in yield of wheat at increased CO2 at 700 ppm and 850 ppm was studied. The effect of different combinations of increased temperature and CO2 on wheat yield was also studied. Simulated wheat productivity revealed the reduction in grain yield by 7.4 to 38.6 per cent in response to temperature rise up to 40 C at all locations. The elevated CO2 (from 350 ppm up to 850 ppm) increased the yield by 39.1 per cent. Increased temperature with combination of increased CO2 concentration reduced the yield by 2.1-16.0 per cent for different combinations at different locations. The maximum reduction in simulated wheat yield was observed at combination of 2 o C increase in temperature with 450 ppm CO2 concentration at all locations in Bihar.