Two piperidin derivatives namely 5-(1,3-benzodioxol-5-yl)-1-(piperidin-1-yl)penta-2,4-dien-1-one (piperine: P1) and 5-(1,3-benzodioxol-5-yl)-1-(piperidin-1-yl)pent-2-en-1-one (piperanine: P2) were investigated as corrosion inhibitors for mild steel using density functional theory (DFT) at B3LYP/6-31G(d) level. Quantum chemical parameters most relevant to their potential action as corrosion inhibitors such as EHOMO (highest occupied molecular orbital energy), ELUMO (lowest unoccupied molecular orbital energy), energy gap (ΔE), dipole moment (μ), electron affinity (A), ionization potential (I), absolute electronegativity (χ), global hardness (η), softness (S), fraction of electrons transferred (ΔN), electrophilicity index (ω) and back-donation (ΔEback-donation), have been calculated and discussed. The theoretical results were found to be consistent with the experimental data reported.