Unconfined compression tests are commonly performed for the analysis of bearing capacity, slope stability and other engineering issues. This paper studies the unconfined compression strength of unsaturated Completely Decomposed Granite (CDG) soil mixed with different percentages of marine clay at different water contents. The filter paper technique was adopted to estimate soil matric suction. A series of Soil-Water Characteristic Curves (SWCC) were obtained for the unsaturated CDG, marine clay and their mixtures. The obtained SWCC curves were fitted using Fredlund & Xing equation and the effect of clay fraction on the fitting parameters are analyzed and discussed. Shear stress and strain relationships from unconfined compression tests are presented and discussed. It is observed that the soil shows strain hardening behavior at low suctions. But at large suctions, a significant softening behavior is seen after a rapid increase in shear stress at the beginning of compression. © 2015 Taylor & Francis Group.