A technology for the modifying treatment of the wood fiber boards (WFB) by a solution of a petropolymer resin obtained from C9-fraction is considered. The technological process of modification of WFB included a number of operations on samples preparation, impregnation in a modifying composition and thermal hardening of the prepared composites. The process of the WFB modification was studied applying an experimental planning method based on a scheme of the greek-latin square of the forth order.