In fabricating metal matrix composites, it is important to evaluate the coherence at the interface between the reinforcements and the matrix metal. Titanium particulates were selected as suitable reinforcements in this study because they had high hardness and Young’s modulus compared to the magnesium alloys used as the matrix, and also showed better ductility than those of ceramic particles. The wettability in the combination of pure magnesium and pure titanium was investigated in this study. The sessile drop method indicated that the contact angle in the case of Mg-Ti was 40°at 1073K in argon gas atmosphere, and showed an excellent wettability of pure titanium by molten pure magnesium. No intermetallic compound at the interface between them was detected. Titanium particulate could be effective reinforcements of magnesium composite materials. Water-atomized magnesium composite powders including titanium particles were used as raw materials, and consolidated by cold compaction and hot extrusion. When including about 3 mass% Ti particles, the magnesium composites reinforced with them showed significantly improved yield stress and tensile strength, while having good elongation.