Most cereal bowls are made microwave and dishwasher-safe, and you’ll rarely ever come across one that you can’t put into a microwave for short periods of time. The oven, on the other hand, is a completely different thing. You won’t be able to put any bowls made out of plastics or wheat straw fiber in the oven. You can, however, use glass and porcelain bowls in the oven if you need to. But if you need to bake something small in the oven, I would suggest you use ramekins instead – they’re made for this kind of stuff, while your glass cereal bowls are not!