Three alkaline earth metal salts of phenylacetic acid were examined and all were found to have similar structural types to analogous salts of benzoic and halobenzoic acids. Thus, a synchrotron study shows that the cations in catena-poly[[[tetraaquamagnesium(II)]-μ-phenylacetato-κ(2)O:O'] phenylacetate], {[Mg(C(8)H(7)O(2))(H(2)O)(4)](C(8)H(7)O(2))}(n), form a one-dimensional coordination polymer that propagates through Mg-O-C-O-Mg interactions involving both crystallographically independent Mg centres (Z' = 2) and through translation along the a axis. The polymeric chains pack to give alternate inorganic layers and organic bilayers. The Ca and Sr species catena-poly[[[diaqua(phenylacetato-κ(2)O,O')calcium(II)]-μ(3)-phenylacetato-1':1:1''κ(4)O:O,O':O'] monohydrate], {[Ca(C(8)H(7)O(2))(2)(H(2)O)(2)]·H(2)O}(n), and catena-poly[[[diaqua(phenylacetato-κ(2)O,O')strontium(II)]-μ(3)-phenylacetato-1':1:1''κ(4)O:O,O':O'] monohydrate], {[Sr(C(8)H(7)O(2))(2)(H(2)O)(2)]·H(2)O}(n), are essentially isostructural. Both form one-dimensional coordination polymers through a carboxylate group that forms four M-O bonds. The polymeric chains propagate via 2(1) screw axes parallel to the b axis and are further linked in the bc plane by hydrogen bonding involving the non-metal-bound water molecule. Similarly to the Mg salt, both have inorganic layers that alternate with organic bilayers.