This paper reports a study on leak detection of a household gas supply system using pressure decay method. The leak is detected by monitoring the pressure decay of a pipe. Since pressure is influenced by temperature, a temperature change will influence the accuracy of leak detection using pressure decay method. This research focuses on the study of the effect of temperature change to the pressure responses of pipe. Experiments were done by recording the pressure responses of pipe and room/environment temperature at several points in various room temperatures, various leak rates and at 2kPa of supply pressure. The pipe length and diameter were varied. The system was mathematically modeled. Its pressure and temperature responses were simulated. The simulations were done under three different conditions: a) Pressure responses of pipe subjected to pipe temperature change during charging, b) Pressure responses of pipe subjected to room temperature change and c) Pressure responses of pipe subjected to temperature fraction of gas within the pipe. The simulation results were compared with the experimental results and show that room temperature change has the highest effect on the pressure response of pipe.