The hydrogenation properties of the cubic Laves phase CaRh2 and the formation of the perovskite CaRhH3 were studied by in situ thermal analysis (differential scanning calorimetry), sorption experiments, and in situ neutron powder diffraction. Three Laves phase hydrides are formed successively at room temperature and hydrogen gas pressures up to 5 MPa. Cubic alpha-CaRh2H0.05 is a stuffed cubic Laves phase with statistically distributed hydrogen atoms in tetrahedral [Ca2Rh2] voids (ZrCr2H3.08 type, Fd (3) over barm, a = 7.5308(12) angstrom). Orthorhombic beta-CaRh2D3.93(5) (own structure type, Pnma, a = 6.0028(3) angstrom, b = 5.6065(3) angstrom, c = 8.1589(5) angstrom) and gamma-CaRh2D3.20(10) (beta-CaRh2H3.9 type, Pnma, a = 5.9601(10) angstrom, b = 5.4912(2) angstrom, c = 8.0730(11) angstrom) are low-symmetry variants thereof with hydrogen occupying distorted tetrahedral [Ca2Rh2] and trigonal bipyramidal [Ca3Rh2] voids. Hydrogen sorption experiments show the hydrogenation to take place already at 0.1 MPa and to yield beta-CaRh2H3.8(2). At 560 K and 5 MPa hydrogen pressure the Laves phase hydride decomposes kinetically controlled to nanocrystalline rhodium and CaRhD2.93(2) (CaTiO3 type, Pm (3) over barm, a = 3.6512(2) angstrom). The hydrogenation of CaRh2 provides a synthesis route to otherwise not accessible perovskite-type CaRhH3.