The effect of thermal treatment and impregnation of woods on the stability of wood colour was investigated. Impregnation was performed by extractives obtained from the same thermally treated species or different ones. Treated and untreated samples were exposed to an accelerating ageing by solar radiation during 1000 h. Resuts showed that thermal treatments improved mainly the colour stability of softwood (pine and white fir) samples. Analysis of chromatic coordinates after 1000 hours of accelerated ageing showed that, thermally treated pine and white fir woods were the least affected samples with E* 1000 = 8.66 and 13.31 respectively. Impregnation increases the component b* causing an intense darkening of all analysed wood samples. Moreover, impregnation stabilised the colour of poplar and fir woods subjected 1000 hours of accelerated ageing whereas, beech woods showed high variations in colour. Thus, thermal treatment and impregnation could stabilise the surface aspect of woods that have an unstable natural colour. The efficiency of impregnation depends on the nature and physicochemical properties of the extractable substances and thus on wood species.