Synthesis of benzimidazolone derivatives containing heterocyclic moieties has received great attention because they exhibit a wide range of biological activities and are used as building blocks in the manufacture pharmaceuticals, agrochemicals, inhibitors, pigments, herbicides and fine chemicals. These derivatives are conventionally synthesised by using harmful chemicals like phosgene, etc. Thus, developing a cleaner synthetic route is more desirable according to principles of green chemistry. The main objective of the current work was to invent a green route for the synthesis of 1, 3- dihydro-benzimidazol-2-one selectively by carbonylation of o-phenylene diamine (OPDA) using heterogeneous catalyst. The co-product of the reaction is water whereas CO2 was used as a carbonylating agent which is one of the major greenhouse gases and no organic co-catalyst was used. Among Li/MgO, ZrO2, La-Zr mixed oxide and calcined hydrotalcite, La-Zr (1:3) mixed oxide catalyst was the best. The study involves the optimization of various process parameters such as concentration, temperature, pressure, catalyst loading, etc. to intensify the conversion of OPDA and understand the kinetics of reaction. The optimized conditions for the reaction were 170 °C, 3.5 MPa of CO2, 0.01 mol OPDA concentration, 1.33 × 10−2 g/cm3 catalyst loading, speed of agitation of 1000 rpm, methanol (30 mL) as solvent and La-Zr mixed oxide as the catalyst. The catalyst was reusable over three catalytic cycles without any loss of activity. The reaction follows first order kinetics. The activation energy for the reaction was 21.2 kcal/mol.