Wash your coffee mug in warm, soapy water with a microfiber cloth or small sponge. If your mug has a removable liner or lid, wash these pieces as well.
Scrub away coffee stains with a nonabrasive scrubbing pad. If you have a tough stain, sprinkle baking soda on the pad and then scrub.
If you have a stain that won't wear away, rinse out the mug, fill it with distilled white vinegar, set it aside to soak overnight and try scrubbing again.
Rinse the mug thoroughly after you wash it to remove detergent residues.
Place the mug in a dish drainer to air-dry or hand dry with a soft, dish towel.