A demulsification composition for demulsification of water-in-oil emulsion caused due to wash water in the crude oil, wherein the composition comprises: a. a compound selected from the group comprising: (i) glyoxal, (ii) neutralized glyoxal, and (iii) a mixture thereof; and b. at least one demulsifier, wherein the demulsifier is selected from the group comprising: (i) condensation product of: i) nonyl phenol and amyl phenol, and formaldehyde; ii) nonyl phenol and butyl phenol, and formaldehyde; iii) nonyl phenol and formaldehyde; iv) amyl phenol and formaldehyde; v) butyl phenol and formaldehyde; vi) alkyl phenol and formaldehyde; or vii) a mixture thereof; (ii) condensation product of: i) cardanol, nonyl phenol and amyl phenol, and formaldehyde; ii) cardanol, nonyl phenol and butyl phenol, and formaldehyde; iii) cardanol, nonyl phenol and formaldehyde; iv) cardanol, amyl phenol and formaldehyde; v) cardanol, butyl phenol and formaldehyde; vi) cardanol, alkyl phenol and formaldehyde; or vii) a mixture thereof; (iii) oxyalkylated condensation product thereof; (iv) oxyalkylated condensation product thereof obtained by oxyalkylation with ethylene oxide, propylene oxide, butylene oxide or mixtures thereof; (v) oxyalkylated copolymer or oxyalkylated polymer of the condensation product. a. a compound selected from the group comprising: (i) glyoxal, (ii) neutralized glyoxal, and (iii) a mixture thereof; and (i) glyoxal, (ii) neutralized glyoxal, and (iii) a mixture thereof; and b. at least one demulsifier, wherein the demulsifier is selected from the group comprising: (i) condensation product of: i) nonyl phenol and amyl phenol, and formaldehyde; ii) nonyl phenol and butyl phenol, and formaldehyde; iii) nonyl phenol and formaldehyde; iv) amyl phenol and formaldehyde; v) butyl phenol and formaldehyde; vi) alkyl phenol and formaldehyde; or vii) a mixture thereof; (ii) condensation product of: i) cardanol, nonyl phenol and amyl phenol, and formaldehyde; ii) cardanol, nonyl phenol and butyl phenol, and formaldehyde; iii) cardanol, nonyl phenol and formaldehyde; iv) cardanol, amyl phenol and formaldehyde; v) cardanol, butyl phenol and formaldehyde; vi) cardanol, alkyl phenol and formaldehyde; or vii) a mixture thereof; (iii) oxyalkylated condensation product thereof; (iv) oxyalkylated condensation product thereof obtained by oxyalkylation with ethylene oxide, propylene oxide, butylene oxide or mixtures thereof; (v) oxyalkylated copolymer or oxyalkylated polymer of the condensation product. (i) condensation product of: i) nonyl phenol and amyl phenol, and formaldehyde; ii) nonyl phenol and butyl phenol, and formaldehyde; iii) nonyl phenol and formaldehyde; iv) amyl phenol and formaldehyde; v) butyl phenol and formaldehyde; vi) alkyl phenol and formaldehyde; or vii) a mixture thereof; i) nonyl phenol and amyl phenol, and formaldehyde; ii) nonyl phenol and butyl phenol, and formaldehyde; iii) nonyl phenol and formaldehyde; iv) amyl phenol and formaldehyde; v) butyl phenol and formaldehyde; vi) alkyl phenol and formaldehyde; or vii) a mixture thereof; (ii) condensation product of: i) cardanol, nonyl phenol and amyl phenol, and formaldehyde; ii) cardanol, nonyl phenol and butyl phenol, and formaldehyde; iii) cardanol, nonyl phenol and formaldehyde; iv) cardanol, amyl phenol and formaldehyde; v) cardanol, butyl phenol and formaldehyde; vi) cardanol, alkyl phenol and formaldehyde; or vii) a mixture thereof; i) cardanol, nonyl phenol and amyl phenol, and formaldehyde; ii) cardanol, nonyl phenol and butyl phenol, and formaldehyde; iii) cardanol, nonyl phenol and formaldehyde; iv) cardanol, amyl phenol and formaldehyde; v) cardanol, butyl phenol and formaldehyde; vi) cardanol, alkyl phenol and formaldehyde; or vii) a mixture thereof; (iii) oxyalkylated condensation product thereof; (iv) oxyalkylated condensation product thereof obtained by oxyalkylation with ethylene oxide, propylene oxide, butylene oxide or mixtures thereof; (v) oxyalkylated copolymer or oxyalkylated polymer of the condensation product.