Unlubricated friction and wear behaviors of TiN coating in contact with AISI 01 steel were investigated as a function of the reciprocating sliding cycle (sliding distance) using a block-on-ring wear test machine. The applied load was 109 kgf and the linear velocity was 0.07 m s-1. The microstructural and chemical characterization of wear surfaces and debris by scanning electron microscopy and energy- and wavelength-dispersive X-ray spectrometry are presented. The correlation between wear characteristics and microstructures of wear surfaces and debris is described. The mechanisms of the wear process at various stages are characterized.