Microstructure of the Ti-24Al-14Nb-3V-0.5Mo (at.%) alloy deformed from room temperature to 700°C was studied by the H-800 transmission electron microscope (TEM) equipped with a side entry goniometer stage capable of ±45° tilt on the X or Y axis operating under two-beam condition. Especially dislocation types and slip systems of the α2-phase (D019) were analyzed in accordance with \(\overrightarrow g \cdot \overrightarrow b \) invisibility criterion. The results indicated that with increasing the deformation temperature from room temperature to 700°C, the slip of \(\overrightarrow a \)-type dislocations on prismatic planes \({\text{\{ 10}}\overline {\text{1}} {\text{0\} }}\) in the α2-phase was enhanced whereas that on basal plane (0001) with hexagonal networks morphology was suppressed during tensile deformation. Being immobile, the dislocation networks were thought to be mainly responsible for the low ductility at low temperature. When the test temperature was increased to 700°C, the \(\overrightarrow {\text{c}} {\text{ + }}\overrightarrow {\text{a}} {\text{/2}}\)-type dislocation glide on pyramidal planes \({\text{\{ 0}}\overline {\text{2}} {\text{21\} }}\) was also observed, but the hexagonal dislocation networks formed by the slip of \(\overrightarrow {\text{a}} \)-type dislocations on basal planes were hardly seen. During the high temperature deformation microstructural refinement was also observed due to dynamic recovery and recrystallization. This, together with the precipitation of secondary α2 phase and O phase during deformation all contributed to ductility of the present alloy at high temperature.