Metal octadecylphosphonate Langmuir-Blodgett (LB) films of a series of divalent and trivalent metals have been prepared and characterized. The films are each shown to be LB analogs of known solid-state metal organophosphonates possessing a two-dimensional ionic-covalent metal phosphonate network. The metal phosphonate lattice crystallizes during the LB deposition process. LB films of octadecylphosphonic acid with Mn2+, Mg2+, Co2+ and Cd2+ form with the stoichiometry M-II(O3PC18H37)H2O and have metal binding consistent with the analogous M-II(O3PR)H2O layered solids. The Ca2+ and Ba2+ films form structures with stoichiometry M-II(HO3PC18H37)(2), and octadecylphosphonate LB films of La3+, Sm3+ and Gd3+ form with stoichiometry M-III(HO3PC18H37)(O3PC18H37) and have structures consistent with the analogous M-III(HO3PR)(HO3PR) layered solids.