The nanostructured cubic GaSb phase was produced after 2h of milling by mechanical alloying (MA). Structural and thermal properties from the as-milled and annealed samples were investigated using X-ray diffraction (XRD), differential scanning calorimetry (DSC) and open photoacoustic cell (OPC) techniques. The measured XRD pattern for the annealed sample showed the same cubic GaSb phase more antimony segregation. The thermal diffusivity, surface recombination velocity, diffusion coefficient, and relaxation time values were obtained for both samples by analyzing the OPC photoacoustic data.