The present invention relates to a process for the purification of methylcobalamin, namely from iron cyanide impurities, comprising contacting a solution comprising methylcobalamin and iron cyanide anions with a strongly basic anion exchange resin. This purification process can advantageously be used for removing iron cyanide impurities from methylcobalamin obtained by reductive methylation of cyanocobalamin and wherein iron (II) salts are used as cyanide scavengers, thus providing methylcobalamin with a reduced iron content. Methylcobalamin (R is methyl).