The nickel based Colmonoy 5 alloy powder was deposited on 316 L (N) austenitic stainless steel substrate. In order to examine the effects of aging treatment on the wear behavior of a nickel based hardfacing alloy, the as-deposited coating was aged at 580°C for 5000h in ambient atmosphere. Coating microstructures were characterised by scanning and transmission electron microscopy. Sliding tests were conducted under self mated condition at room temperature and 550°C using a pin-on disc type apparatus. The wear loss of the aged coating was found to be higher than that of the as deposited coating. The coarse grained structure with carbide (Cr23C6) precipitation in the aged coating would account for the higher sliding wear loss. However, the aged coating, with reduced hardness exhibits similar wear behavior of as deposited coating during sliding at 550°C. © (2011) Trans Tech Publications.