The report introduces simple yet highly reactive calcium salt, Ca[Al(OR^F)₄]₂ (R^F=C(CF₃)₃), 1, which effectively catalyses olefin hydrosilylation through an unusual mechanism involving the activation of the alkene molecule. Upon dissolution in o-difluorobenzene (oDFB), 1 forms a highly Lewis acidic [Ca(oDFB)₆]²⁺ complex. Our DFT calculations reveal that fluoride ion affinity is comparable to SbF₅. Reactivity tests show that it effectively catalyses the hydrosilylation of olefins with high regioselectivity, also in reactions involving sterically demanding substrates like (iPr)₃SiH or tetrasubstituted olefins. Experimental and computational results point to the mechanism where the olefin molecule forms a complex with Ca²⁺, which significantly facilitates the attack of H-SiR₃ on the C=C double bond.