Biocomposite boards from red wine grape pomace (WGP; Pinot Noir) or white WGP (Morio Muscat) were investigated on the basis of crosslinking and thermal compression mechanisms. We used an orthogonal experimental design to optimize the formulations by examining the effects of binder type, pomace-to-binder (P/B) ratio, and hydrophobic and crosslinking agents on the mechanical properties, water sensitivity, and biodegradability of the board. The optimized formulations were as follows: (1) for red WGP boards, soy flour (SF) or soy protein isolate (SPI) and poly(vinyl alcohol) (PVA; 1 : 1) as binders at a P/B ratio of 19 : 1 with 1% stearic acid (SA) and 1% epichlorohydrin and (2) for white WGP boards, SF or SPI-PVA (1 : 1) as binders, with a P/B ratio of 4 : 1, and 1% SA. The red WGP boards showed a high break strength and modulus of elasticity with a moderate percentage strain value, whereas the white WGP boards had a high flexibility and biodegradability. After burial in soil for 30 days, the red and white WGP boards degraded by about 50 and 80%, respectively. Microstructure studies indicated that the use of binders and other functional agents resulted in a compact fracture surface of the WGP biocomposite boards. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 119: 2834-2846, 2011