[en] Thermal expansion and magnetostriction measurements have been made on the cubic Laves-phase alloys Ho(Co_1-xRh_x)₂ in the temperature range 2 to 110 K and in fields up to 7 T. The samples were polycrystalline, with x=0.00, 0.02, 0.05, 0.08, 0.12, 0.16 and 0.25. Two thermal expansion anomalies are observed at a ferromagnetic transition and a spin-flop transition. The change in temperature and ordering nature of these transitions is reported as a function of Rh concentration. Magnetostriction measurements show a marked variance with Rh concentration and suggest the presence of three new distinct magnetic phases. ((orig.))