Clean the interior of the microwave thoroughly with a degreasing cleanser and wet cloth. Dry with a towel.
Scrape the peeling paint with a putty knife.
Sand the rough sections of the interior with 220-grit sandpaper. Apply masking paper and painter's tape to cover the areas you do not want to paint.
Apply a coat of acrylic latex primer to the area of peeling paint. If your microwave has a metalic surface, use galvanized metal etching spray instead. Allow the surface to dry for four hours.
Apply a coat of acrylic spray enamel or epoxy spray paint to the surface of the damaged area. Allow four hours for the surface to dry before using your microwave again.