Oxidative addition of bulky primary, secondary, and tertiary silanes to PNP (PNP = [N(2-(PPr2)-Pr-i-4-Me-C6H3)(2)](-)) iridium complexes (PNP)IrH2 and (PNP)Ir(COE) (11) afforded iridium silyl hydride complexes (PNP)Ir(H)(SiRR'R '') (3-8). Addition of 2 equiv of PhSiH3 or (3,5-Me2C6H3)SiH3 to (PNP)IrH2 or 11 yielded disilyl complexes (PNP)Ir(SiH2R)(2) (R = Ph (9), 3,5-Me2C6H3 (10)). Hydride abstraction from (PNP)Ir-(H)(SiH2R) (R = Trip (5), Dmp (6)) by [Ph3C][B(C6F5)(4)] afforded iridium silylene complexes [(PNP)(H)Ir=SiR(H)][B(C6F5)(4)] (R = Trip (12), Dmp (13)) exhibiting downfield Si-29 NMR resonances (234 ppm (12), 226 ppm (13)) and downfield H-1 NMR resonances for the Si-H group (10.76 ppm (12), 9.76 ppm (13)). Thermally stable disubstituted silylene complexes [(PNP)(H)Ir=SiPh2][A] (A = B-(C6F5)(4) (14), -CB11H6Br6 (16)) were isolated via hydride abstraction from (PNP)Ir(H)(SiHPh2). The X-ray structure of 16 confirmed sp(2) hybridization at silicon and revealed a short Ir-Si bond of 2.210(2) angstrom. Catalytic hydrosilation of alkenes by hydrogen-substituted silylene complexes [(PNP)(H)Ir=SiMes(H)][B(C6F5)(4)] (1) and 14 exhibited anti-Markovnikov regioselectivity with an array of alkene substrates. Addition of H(3)SiMes to complex 1 afforded [(PNP)(SiH(Mes)(Hex))IrH(SiH(2)Mes)][B(C6F5)(4)] (19), featuring a beta-agostic interaction demonstrated by a J(SiH) Of 102 Hz for the N-SiH hydrogen. Similarly, addition of H2SiPh2 to 16 afforded the structurally characterized Ir(V) disilyl complex [(PNP)(SiPh2)Ir(SiPh2H)(H)(2)][CB11H6Br6](20). Complex 20 was found to be catalytically active for the hydrosilation of alkenes, which is consistent with its intermediacy in the catalytic cycle.