In the footsteps of previous research on zýkaite (Majzlan J., Amoako F.Y., Kindlová H., Drahota P. (2015): Thermodynamic properties of zýkaite, a ferric sulfoarsenate. Applied Geochemistry 61, 294-301, DOI) we published in Hydrometallurgy new thermodynamic data for FeAsO4·0.75H2O: Majzlan J., Dachs E., Benisek A., Drahota P. (2016): Thermodynamic properties of FeAsO4·0.75H2O – a more favorable disposable product of low As solubility. Hydrometallurgy 164, 136-140 (DOI).