Tropical woods like ebony (Diospyrus ssp.) or rosewood (Dalbergia ssp.) are typical tonewoods used to produce guitar fretboards. Trade of these woods is strongly restricted by CITES (Convention of International Trade in Endangered Species). Furthermore, there is an increasing demand for guitars built without tropical woods. Therefore, it is necessary to search for alternatives. Most native woods in Europe do not meet the requirements that are important for usage in guitar fretboards. These requirements are a sufficiently high hardness and density, dimensional stability and a dark wood colour. To achieve these properties a two-step modification was applied. In a first step wood samples of beech (Fagus sylvatica) and maple (Acer ssp.) were heat-treated at 220 °C for 4 h under nitrogenous atmosphere, followed by an impregnation with a 15% (solid content) solution of phenolic resin (PF). After treatment, the wood was dried stepwise closing with a curing step. The effect of the two-step treatment on dimensional stability, Brinell-hardness and L*a*b*-values were measured. Thermally treatment of beech and maple wood at 220 °C for 4 h changed the light wood colour to dark brown/black. Impregnation of the thermally treated wood with a 15% solution of PF resin resulted in an increase of hardness of 8% for beech and a slight decrease of 5% for maple. Density could be increased by 1.6% for beech and 11.6% for maple wood. The ASE (Anti-Swelling-Efficiency) values of thermally and PF-resin impregnated (TPF)-beech (51% in tenth cycle) and TPF-maple (52% in tenth cylce) were higher than for the thermally treated (T) and the resin impregnated (PF) wood. The ASE values of TPF treatment are stable over ten cycles. The properties of TPF-treated beech meet those of rosewood.