Boron compounds are very effective biocides at relatively low concentrations. On the other hand they do have small negative impacts on human health and environment. Unfortunately, boron compounds do not react with wood, and therefore are prone to leaching. To improve fixation and efficacy, boron compounds were mixed with ethanolamine and quaternary ammonium compound (quat). Borax and boric acid were used as boron source. Standard SIST EN 1250 served as a guideline for fixation studies; SIST EN 113 procedure was used for fungal decay testing, and SIST EN 152 as protocol for blue stain experiments. All the specimens, with the exception of those used for blue stain testing, were made of Norway spruce wood. They were treated with aqueoussolution of the following boron and quat concentrations: 1.0 %, 0.5 % and 0.1 %. Even the specimens impregnated with preservative solution of the lowest concentration were resistant against decay, while higher concentration of active ingredients was necessary to preserve pine sapwood against blue staining. On average 52.6 % boron compounds leached from wood during the process of leaching, having a slightly better value compared to commercial wood preservatives. Furthermore, FTIR analysis showed that depolymerization of lignin appeared, but this phenomenon did not influence boron leaching.