A storing and mixing device (1) comprising a first chamber (2) to store a first substance and a second chamber (4) to store a second substance, the chambers (2, 4) being removably attached to each other. An opening (26) is located between the two chambers (2, 4) which is sealed by a plugging device (24) housed in the first chamber (2). Operation of an actuation means (32), located on a lid (20) of the first chamber (2), contacts and engages with the plugging device (24) in order to remove the plugging device (24) from the opening (26). The contents of the two chambers (2, 4), for example, powdered baby formula and hot water, are then permitted to mix.
