Abstract: Methods for surface modification of wood-fiber reinforced thermoplastic composites (WPCs) for improving surface adhesion of a water-based acrylic coating and composites having such surface properties are disclosed herein. In one embodiment, the surface of WPC formulations can be modified using one or more surface treatments including chromic acid treatment, oxygen plasma treatment, Benzophenone/UV treatment, and flame treatment. In another embodiment, WPC material can be sequentially treated with chromic acid and oxygen plasma to roughen the WPC material surface and increase the WPC surface wettability with polar liquids. In some embodiments, an acrylic coating peel load increased approximately 64% to approximately 170% following surface modification.