We present a complete calculation of the leading-order QCD corrections to the quark level decay amplitude for b→ s γ γ and study their relevance for both the inclusive branching ratio B (B→ X s γ γ) and for the exclusive decay channel B s→ γ γ. In addition to the uncertainties in the short distance calculation, due to the choice of the renormalization scale, an appreciable uncertainty in both B s→ γ γ and B→ X s γ γ is introduced by the matrix element calculation. We also briefly discuss some long distance effects, especially those due to the η c resonance for the inclusive rate. Finally, a brief analysis of the IR singularities of the two photon spectrum in the inclusive case is given.