The present invention relates to a method for bringing a powder and a liquid component, preferably polymer and monomer, in contact with each other for mixing thereof, preferably to form bone cement, wherein the powder component (P) is placed in a mixing container (1) in which the mixing shall occur and the liquid component (M) in a liquid container (18) from which said the liquid component (M) is transferred to the powder component (P) in the mixing container (1). In this method, a vacuum is generated in the mixing container (1) and the liquid container (18) is opened by means of at least one cannula (14) or similar member through which the liquid component (M) can be brought to flow from the liquid container (18) to the mixing container (1). The vacuum is brought to suck the liquid component (M) from the liquid container (18), through the cannula (14) and into the mixing container (1) to the powder component (P) therein, and/or is the liquid component (M) pressed into the mixing container (1) through the cannula (14) while the liquid container (18) is compressed because of the pressure difference between the vacuum in the interior of the liquid container (18) and the air pressure outside the liquid container. The invention also relates to a device for carrying through the method.