silica supports modified by grafting groups polyalkylguanidinium, process for obtaining them and their application as a phosgenation catalyst.

silica support surface modified by grafting by covalent bond of organic groups polysubstituted guanidinium, and preferably polyalkylguanidinium groups. These supports may be obtained by reacting silica with polyalkylguanidinium anion. The residual silanol silica functions can be treated with hexamethyldisilazane to stabilize media. These supports can be used as phosgenation catalyst.