Periodic density functional slab models were used to investigate adsorption of methoxide and its decomposed intermediates on optimized and strained (-5% to +5%) Cu(100) surfaces. Surface relaxation energies and adsorption energies of methoxide and its decomposed intermediates were systematically studied and quantified. Reaction energetics of methoxide C-H and C-O bond breaking were quantified on the strained Cu(100) surfaces.