Integrated gasification combined cycle (IGCC) power plant offers efficient power generation due to possibility of co-firing (i.e., coal with biomass), co-production (electricity, methane, ammonia, etc.) and ease of carbon capture. Thermo-economic analysis of the IGCC power plant is carried out to assess its performance under flexible operation. Motivation of flexible operation comes from the demand variation and volatility of market prices. At the time of peak electricity demand, production of methane and ammonia may be reduced to meet peak electricity demand at high selling price to increase the total product value. Effect of capture level reduction on the total product value is also considered. Various scenarios for the production of electricity, methane and ammonia were generated and simulations were performed for all these scenarios using Aspen Plus. Then, nine scenarios for variation in market price were considered and economic analysis was performed. This thermoeconomic analysis has shown that total product value can be increased significantly by changing the production decisions against the variable market prices. The total product value was more sensitive to the variations in electricity market price as compared to methane and ammonia prices. However, the effect of capture level reduction was not found to be significant.