The effects of Al content on microstructure, phase transformation and activation energy of Ti-12V-xAl (x = 2, 4 and 6 wt %) alloys produced by using the arc-melting technique have been investigated in the present study. These features of the alloys were characterized using X-ray diffraction (XRD), scanning electron microscope (SEM), differential scanning calorimetry (DSC) and transmission electron microscopy (TEM). The XRD and SEM measurements showed that the alloys had simple of single orthorhombic a. martensitic phase. In the DSC analysis, it was observed that the martensitic transformation temperature decreased depending on the heating rate in the alloys. The highest transformation temperature occured in the Ti-12V-4Al alloy. In TEM images, it was noteworthy that there were martensite structures arranged side by side in the structure of the alloys. The activation energies of the alloys were estimated using the Kissenger and Osawa method using the data obtained from DSC. Activation energies determined by these two methods were similar.