The cosmic γ-ray spectrum below 1 GeV arising from cosmic ray p-p interactions is calculated. Its characteristics are determined by the properties of secondary neutral pion production occurring at accelerator energies. A model is chosen for numerical calculations in which the two dominant modes of neutral pion production at accelerator energies are the production of the Δ (1.238) isobar and one fireball. The effect of α-p and p-α interactions on the cosmic γ-ray spectrum is also calculated. The final results are given in terms of both differential and integral γ-ray energy spectra.