This study evaluates the decay and termite resistance of wood treated with didecyl dimethyl ammonium tetrafluoroborate (DBF), a recently developed quaternary ammonia compound containing boron. Laboratory decay resistance tests were performed using brown-rot fungus, Fomitopsis palustris and white-rot fungus, Trametes versicolor. Treated wood specimens were also subjected a 3-week-termite resistance test using subterranean termites, Coptotermes formosanus. Decay resistance tests showed that wood specimens treated with 0.5 and 1.0% DBF solutions were well protected against both fungi even after a 10-day severe leaching process, suggesting the adequate fixation of DBF in wood. DBF treatment at 0.1% concentration was efficient against subterranean termites, Coptotermes formosanus Shiraki based on mass losses in both leached and unleached wood specimens. The ability of DBF to inhibit discolorations by selected mold and stain fungi was also screened in laboratory conditions. DBF at the highest concentration level (1%) provided limited protection against mold and staining fungi tested, however, it was effective for only short-term protection (1 or 2 weeks) at lower concentrations. These results suggest that DBF is promising to protect wood to be used outdoors against both fungal decay and termite attack however field tests are needed to observe the performance of DBF-treated wood in ground contact.