The present invention relates to a method for manufacturing a film having an oxygen transmission rate in the range of from 1 cc/m2/24 h to 500 cc/m2/24 h according to ASTM D-3985, at a relative humidity of more than 50% at 25° C., or higher than 75% at 25° C., or higher than 85% at 25° C., wherein the method comprises the steps of: providing a first suspension comprising a microfibrillated cellulose, wherein the dry content of the suspension is in the range of from 0.1 to 10% by weight, adding a wet strength additive to said first suspension, at an amount of from 0.1 to 10 weight-% based on the amount of microfibrillated cellulose (dry/dry), thereby forming a mixture of the microfibrillated cellulose and the wet strength additive, applying said mixture to a substrate to form a fibrous web and drying said web to form said film. The present invention also relates to a film produced according to the method.