This research is aimed at evaluation the suitability of wood ash for use in stabilization of expansive black cotton soil. Laboratory work was conducted to determine various geotechnical properties of soil sample and the index properties. These result used to classify the soil sample. To evaluate the properties of wood ash, various laboratory tests are performed. The preliminary investigation of this soil shows that it belongs to A-7-5 class of soil according to the AASHTO soil classification system. Soils under this class are generally of poor engineering quality. The test is conducted simply by adding wood ash in different percentage. Wood ash is added in stepped mass percentage of 5%, 10%, 15%, and 20% by dry weight of the soil. When wood ash,lime and fly ash are compared with respect to liquid limit(LL), plasticity index(PI), shrinkage limit(SL), free swell, CBR swell and CBR, their values are variation pattern tend to be similar. The difference among these material are in the amount of additives that need to be added to the untreated soil sample to improve their characteristics. On the other hand ,the specific gravity, plastic limit(PL),optimum moisture content (OMC) and maximum dry density (MDD) of fly ash treated soil were not similar pattern like wood ash and lime treated soils. But ,the soil treated by wood ash and lime have similar graphical patterns and behaviors. Therefore we conclude that wood ash is used as soil stabilizer materials,like lime and other additives.