It is not a good idea to put melamine cups into the microwave. Melamine is a plastic material that absorbs microwaves and may heat up and release toxic chemicals.
Melamine cups must not be placed in the microwave. Almost all of the dinnerware has a warning against microwave use, so I would not take the chance with your cups.
melamine is not suitable for use in microwave ovens. In high wattage ovens, melamine can start releasing toxic gases, and can ignite suddenly. It is not safe.
