Ni-based superalloys possess desirable high-temperature properties including strength, ductility, fracture toughness as well as resistance to creep and oxidation. An important factor for strengthening mechanism is the microstructure of the alloy which consists of ordered γ’- Ni3Al precipitates within a γ (Ni-Al) matrix. In addition, a variety of substitutional and interstitial elements like Cr, Ta, Re, Ru, Ti, W, Mo, C, S etc. play a crucial role in strengthening of these alloys. It is thus important to understand the electronic structure and diffusion of these elements. Using density functional theory methods with plane-wave basis sets we determine the partitioning behavior of alloying elements in the interface. We also systematically explore the energetics and kinetics of diffusion of Cr, Mo, C, and O in the bulk and across the γ/γ'’ interface. We use transition state theory combined with nudged elastic band method to determine the transition paths and diffusion activation barriers.