A coolant operating condition in al fuel cell stack was an important factor to determine the temperature distribution which affected the fuel cell performance and relative humidity. In this study, the fuel cell performance was evaluated as a function of the coolant flow rate with the range of $0.1{sim}0.8$ liter/min cell and the coolant inlet temperature of $20{sim}82^{circ}C$. The cell temperature increased with increasing the coolant inlet temperature and with decreasing the coolant flow rate. The coolant inlet temperature and flow rate to maintain the better performance of the fuel cell were in the range of $45{sim}60^{circ}C$ and $0.2{sim}0.4$ liter/min cell, respectively. The experimental results showed that the optimal heat removal rate from the stack by coolant was $0.4{sim}0.6W/cm^2$ cell.