A process for the preparation of an alkylene carbonate, said process comprising contacting the corresponding alkylene oxide with carbon dioxide in the presence of water and in the presence of a catalytic composition comprising an organic base neutralized with a hydrogen halide, wherein the organic base comprises a carbon-based compound comprising one or more nitrogen atoms with at least one free electron pair and/or one or more phosphorous atoms with at least one free electron pair and wherein the organic base has a pKa greater than 8.