Microstructures of Ti50Al45Mo5 (at.%) alloy powders produced by the plasma rotating electrode process (PREP) were investigated. The powders have inhomogeneous structures, which consist of dendrites and rounded grains. The dendrites, which show a “rosettelike” morphology, are formed on the powder surface and around the rounded grains. The rosettelike dendrites are of hexagonal α 2 (D019) phase even though the dendrites have an equiaxial morphology, and a small amount of β 2 (B2) phase is also contained inside. It is suggested that the solidification to α (hcp-A3) phase occurred by the peritectic reaction between the primary β (bcc-A2) dendrites and the liquid: L+β→L+β+α. The rounded grains, on the other hand, are of β 2 phase in which acicular α or α 2 laths are precipitated with the Burgers orientation relationship. Antiphase domain boundaries in the β 2 matrix are intersected by α(α 2) laths. It is interpreted that the α(α 2) laths were formed by the solid-state transformations: β 2→β 2+α→β 2+α 2. The formation of the two different microstructures in the powder particles is rationalized in terms of the changes in local composition of the liquid phase during the rapid solidification process.