As part of our ongoing interest in main group Lewis acids for fluoride anion complexation and element-fluorine bond activation, we have synthesized the stibonium borate salt [Sb(C6F5)(4)][B(C6F5)(4)] (3). The perfluorinated stibonium cation [Sb(C6F5)(4)](+) present in this salt is a potent Lewis acid which abstracts a fluoride anion from [SbF6](-) and [BF(C6F5)(3)](-) indicating that it is a stronger Lewis acid than SbF5 and B(C6F5)(3). The unusual Lewis acidic properties of 3 are further reflected by its ability to polymerize THF or to promote the hydrodefluorination of fluoroalkanes in the presence of Et3SiH. While highly reactive in solution, 3 is a perfectly air stable salt, making it a convenient Lewis acidic reagent.