First time, one-pot oxidative esterification of aldehydes with methanol and hydrogen peroxide as a green oxidant was carried out over Keggin-type cesium salt of nickel substituted phosphotungstate. This protocol affords a novel and efficient approach for achieving high conversion (87%), selectivity for ester (80%) with high turnover numbers (TONs). The catalyst proved to be a bi-functional one, showing synergic effect of lacunary phosphotungstate and nickel by combining their acidic and redox properties. Mechanistic study carried out by UV-Visible spectrophotometer shows that tungsten and nickel both take part in the reaction. The scope of various aldehyde substrates were also evaluated and it was found that the reactions are facile, easy to work up and provide a mild oxidative alternative for organic chemists. (C) 2015 Elsevier B.V. All rights reserved.