Abstract.The formation of formaldehyde from methanol in liver homogenates was almost totally abolished in molybdenum‐deficiency induced by tungstate feeding. The addition of diphosphopyridine nucleotide, adenosine triphosphate or xanthine was not able to increase the formation of formaldehyde from methanol in the molybdenum‐deficient liver homogenates as it did in normal homogenates. The utilisation of added formaldehyde was also depressed in the molybdenum‐deficient homogenates. The liver xanthine oxidase activity fell to very low values after the feeding of tungstate, but the catalase activity of liver was not affected