First-principles density functional theory has been used to evaluate the shear and cleavage strength in terms of Griffith work and generalized stacking fault energy (GSF) of (001) plane for γ, γ′ and γ–γ′ system as a function of distance from the γ/γ′ interface. Calculation of Griffith work suggests higher cleavage energy for bulk γ as compared to γ′ while the GSF calculation suggests higher shear strength for bulk γ′ as compared to γ. It has been found that the shear strength of the cubic plane of the γ/γ′ interface is marginally lower than those of bulk γ and γ′ phases.