The misfit strains of both the isotopic forms of zirconium hydrides, viz., δ-ZrHx and δ-ZrDx, precipitated in zirconium were computed in the temperature range of 298–773 K and for 1.5 ≤ x ≤ 1.7, using the methodology proposed by Carpenter. Misfit strains along (0 0 0 1) plane and normal to it were observed to increase with increase in temperature for both the isotopic forms of hydrides. For a given isotopic atomic fraction, the misfit strains for deuteride were smaller than the corresponding values for hydride and with increase in atomic fraction of hydrogen isotopes, the misfit strains increased.