The crystal and molecular strutures of two solvated forms of [K(18c6)]OAc (18c6 = 18-crown-6 = 1,4,7,10,13,16-hexaoxacyclooctadecane and OAc = acetate) were determined by single-crystal X-ray diffraction, namely (acetato-κ²O,O′)(1,4,7,10,13,16-hexaoxacyclooctadecane-κ⁶O)potassium dihydrate, [K(CH₃COO)(C₁₂H₂₄O₆)]·2H₂O (1) and (acetato-κ²O,O′)aqua(1,4,7,10,13,16-hexaoxacyclooctadecane-κ⁶O)potassium acetic acid monosolvate [K(CH₃COO)(C₁₂H₂₄O₆)(H₂O)]·CH₃COOH (2). In both compounds, the acetate anion is bonded to the potassium ion in a chelating fashion and the metal atom is consequently slightly displaced from the O₆plane of the crown ether. In the crystals, O—H...O hydrogen bonds lead to a polymeric ladder structure in the dihydrate1, while the acetic acid hydrate2features inversion dimers.