The effect of thermo-hygro-mechanical (THM) densification temperature on the surface color, roughness, wettability, and chemical composition of trembling aspen (Populus tremuloides) and hybrid poplar (Populus maximowiczii x P. balsamifera) veneers was investigated. Veneers were subjected to four THM densification temperatures (160 degrees C, 180 degrees C, 200 degrees C, and 220 degrees C). Veneer color darkened with increasing THM densification temperature. Surface roughness decreased between 160 degrees C and 200 degrees C. Wettability decreased after THM densification, but no significant difference was found between treated specimens. ATR-FTIR and XPS results confirmed that THM densification caused major chemical changes in veneer surfaces, and more pronounced at temperatures higher than 160 degrees C. (C) 2010 Elsevier B. V. All rights reserved.