Abstract The mass spectrum of stannane, SnH 4 , has been studied. Ion fragmentation patterns for both the singly and doubly charged fragments were obtained employing 70 V electrons. From appearance potential data, an estimation of the bond energies of the tin-hydrogen bond in the ion-species SnH 3 + H, SnH 2 + H, Sn + H has been made along with ΔH f for SnH 4 . The studies were first made with tin of normal isotopic abundance, and then the results were corroborated with SnH 4 prepared with the separated isotope 120 Sn.