The structural parameters of a second low-temperature form of KZnPO4 have been refined using Rietveld analysis of X-ray powder diffraction (XRPD) data. This form of KZnPO4 is isostructural with NH4ZnPO4I and has previously been denoted as KZnPO4II. This article uses the notation δ-KZnPO4, to be consistent with the α, β, and γ notation commonly used for other KZnPO4 phases.