Solubilities in water and ethanol‐water mixtures as well as the thermal behavior of the food additive calcium propionate were investigated to clarify deviations in published data. Material purified by recrystallization was used to exclude influence of impurities. Investigation of the dissociation process of calcium propionate in aqueous solution indicated that the particular shapes of the solubility curves cannot be attributed to changes in pH. The substance purchased turned out to be a mixture of the monohydrate and anhydrous calcium propionate. A new polymorph of the anhydrous calcium propionate was found and characterized. The results provide a better understanding of calcium propionate and support the development of improved crystallization processes.