Recent interest in using calcium (Ca) as a reinforcement metal in Al/Ca metal-metal composites prompted this study of the mechanical properties of high-purity Ca metal. Previously reported measurements of Ca’s mechanical properties were performed on Ca of relatively low purity (~95 at%). Ca used in this study was purified by sublimation to reduce O, N, and C concentrations, yielding 99.95% purity metal for fabrication of tensile test specimens. Yield strength, ultimate tensile strength, ductility, and strain rate sensitivity of high-purity Ca were measured at both 77K and 295K for annealed and cold-worked Ca. Annealed samples were found to be more strain-rate sensitive than as-swaged samples. Both as-annealed and as-swaged Ca samples were stronger and more ductile at 77K than at 295K, behavior that seems to be supported by molecular dynamics simulations of perfect Ca single crystals.