The superconducting properties of Tc‐V alloys with compositions ranging from 0 to 100 at.% V have been investigated in fields up to 15 kOe by measurements of the bulk magnetization determined ballistically. A phase diagram of the Tc‐V system has been determined by several metallurgical techniques. The sequence of crystal structures at 1500°C with increasing vanadium content is hcp→bcc→CsCl→bcc. The technetiumrich bcc phase when quickly cooled to room temperature exhibits superlattice x‐ray diffraction lines of the CsCl structure. The superconducting transition temperature of the technetium‐rich hcp alloys increases with vanadium concentration from 7.73°K to a maximum for the system of 11.3°K at the limit of vanadium solubility (∼6.5 at.% V). This transition temperature remains constant for the two‐phase alloys. The transition temperature decreases progressively with increasing vanadium content in the CsCl structure, and at compositions in the 50 to 80 at.% V interval no evidence of superconductivity is observed for temperatures as low as 1.4°K. Alloys containing the hcp phase show reversible behavior in the tails of their magnetization curves, while those with the CsCl structure exhibit a high degree of hysteresis in the tails. Estimates of the upper‐critical field at 0°K,HC2(0), using the experimental data and theoretical calculations yield values ofHC2(0) to approximately 45 kOe for the samples with high‐transition temperatures. Results of heat treatment at 1100°C on the superconducting parameters of alloys near the 30 at.% V composition are presented.