The temperature dependence of the elastocaloric effect were studied and experimental values of the adiabatic cooling Δ T ad in loading/unloading cycles up to 13.3 K in quenched and 16.4 K in aged at 573 K, 1 h Ni50.6Ti49.4 single crystals were obtained. In aged crystals, a specific feature of the elastocaloric effect temperature dependence (an increase in Δ T ad above the temperature T R = 273 K) was found, which is associated with a change in the sequence of stress-induced martensitic transformation from R-B19' to B2-B19'. The factors (the value of the dissipated energy in the working cycle, the strain hardening coefficient during the stress-induced martensitic transformation), that affect the elastocaloric effect, are discussed. It is shown, that aged single crystals have a high coefficient of performance value up to 31, which characterizes the efficiency of converting mechanical energy into thermal energy, and are promising for solid-state cooling technologies.