The primary reaction products of laser-ablated uranium atoms with dihydrogen (UH, UH2, UH3, UH4, U2H2, and U2H4) have been isolated for the first time in solid argon and identified by the effects of isotopic substitution on their infrared spectra. Calculations, using DFT methods, have been performed to provide theoretical support for the spectral assignments. The molecules U(mu-H-2)U and U2H4 represent the first examples of an actinide-actinide bond.