This work presents a computational model developed for studying flow behaviour when a transient event, such as a leakage, occurs in a natural gas distribution network. This model is based on the method of characteristics, which was applied to solve the equations that describe a one-dimensional, unsteady, compressible flow that is subjected to heat transfer and friction between the fluid and the pipe walls. In order to validate the computational model, data obtained via simulation were compared with values measured in an experimental setup 140 m in length, which was built using carbon-steel ducts of two inches nominal diameter. Experiments simulating a leakage due to a rupture in a pipework were performed using both compressed air and natural gas. The comparison showed good agreement between simulated and measured values, thus encouraging the utilization of the computational model for field monitoring and geographical location of leakage points along a natural gas network.