A method for preparing a ternary or higher zeotropic refrigerant mixture comprising components of different volatilities is described. The method comprises: mixing together the less volatile components of the mixture in a pre-blending process; and separately adding the most volatile component to the pre-blended mixture by pressure or mass flow control so that the desired initial liquid composition is attained. The liquid zeotropic refrigerant mixture that is prepared may be transferred from a container in which it is held to another container or to a piece of equipment that is to use the refrigerant mixture. This method comprises the steps of: removing at least a portion of the prepared liquid zeotropic refrigerant mixture from a container in which it is held; charging the liquid zeotropic refrigerant mixture that is removed to another container or to a piece of equipment in which it is to be used; and adding at least the most volatile component of the refrigerant mixture to the holding container to compensate for the removal of liquid refrigerant mixture therefrom.