A new methodology is proposed for arsenic, phosphorus and titanium determination in crystalline lamellar phenylarsonate and phenylphosphonate samples by an ICP OES technique. Nitric acid, hydrofluoric acid and hydrogen peroxide were used to decompose mass aliquots of about 50 mg of titanium phenylphosphonate and phenylarsonate in a closed microwave oven. This method was shown to be suitable, reproducible and simple, and the elemental determinations provided the knowledge of the precise stoichiometry of the synthesized compounds. The concentration values obtained from triplicate gave 0.353 ± 0.008 and 0.113 ± 0.003 g g-1 for arsenic and titanium in titanium phenylarsonate samples with relative standard deviations (RSD) 2.3 and 2.7 %, respectively. The titanium phenylphosphonate sample gave phosphorus and metal concentrations of 0.153 ± 0.017 and 0.119 ± 0.003 g g-1 with RSD of 11.1 and 2.5 %, respectively. Based on the obtained results, the molar concentrations for the species were calculated as 4.71 and 2.36 mmol g-1 for the arsenic and titanium elements for phenylarsonate compound, while the values 4.94 and 2.48 mmol g-1 for phosphorus and metal were determined for titanium phenylphosphonate, respectively. The data obtained for these elements in aqueous insoluble inorganic lamellar materials, enable to establish a 2:1 proportion, whose value conformed to the expected and reliable minimum formula for the synthesized Ti(O3PC6H5)2 and Ti(O3AsC6H5)2 compounds.