A class of organosilanes of the general formula ##STR1## wherein Ar is a divalent aromatic radical; R.sub.f is a defined fluoroalkyl or perfluoroalkyl ether group; X is methyl, R.sub.f Ar as defined above, a halogen other than fluorine, or an alkoxy group; and each one of Y and Z is a halogen other than fluorine or an alkoxy group. These organosilanes are very useful as precursors to polysiloxane coupling agents for bonding fluoropolymers to glass fibers which can withstand the usual fluoropolymer melt-processing temperatures without decomposition.