This International Standard specifies methods used to measure the water content of polyols employed as polyurethane raw materials. Method A is a manual amperometric method which has been included to better define the principles of the Karl Fischer measurement. Amperometric methods are applicable to a wide range of polyols, including those which have enough colour to obscure a visual end-point. Method B includes an automated amperometric procedure and an automated coulometric procedure. The coulometric procedure is an absolute method that does not require calibration and gives improved sensitivity compared with amperometric methods.