This paper reports results of an investigation on the blended BWA-FA geopolymer mortars prepared by the inclusion of biomass wood ash (BWA) as a partial replacement material for fly ash (FA). The blended mortar systems were prepared at three replacement ratios of FA by BWA of 5%, 15% and 25% by binder mass. The engineering properties of compressive strength, water absorption and total porosity measurements obtained at different ageing of 3, 7 and 28 days, were used to assess the blended systems against a control mortar mix containing 100% FA. The results showed that the inclusion of BWA up to 15% resulted in higher strength and durability characteristics than the control mix at age of 3 and 7 days. However, at age of 28 days, the geopolymer containing 10% BWA of the total binder was the only blended mixture exhibited higher compressive strength and lower total porosity than the control mix.