The pressure-composition absorption isotherms of deuterium in an alloy with nominal composition V85Ni15 were measured between 87 and 400 degrees C for pressures up to approximate to 17 bar. For T <= 144 degrees C one observes the occurrence of a solid solution alpha phase for D/M < 0.15, the coexistence of alpha and beta phase up to D/M approximate to 0.5 and a subsequent change to a different phase for higher deuterium concentrations. For temperatures higher than 200 degrees C only a solid solution with a deuteration enthalpy Delta H-deutr = 47 +/- 2 kJ/mol is detected. The critical temperature of this V-Ni alloy (144 degrees C <= T*<= 200 degrees C) is much higher than that of pure V (100 degrees C). Moreover, well above the critical temperature, one can observe a "normal" isotope effect, i.e. the equilibrium pressure of the V85Ni15-H system is higher than that of V85Ni15-D. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.