Nicotine is a chemical found in cigarettes. When cigarettes are smoked inside the home, nicotine produces a brown stain that is greasy in nature. Nicotine stains are absorbed into almost every surface with which cigarette smoke comes in contact, including your wood paneling. While the best way to avoid nicotine stains is to prohibit smoking in your home, you can remove nicotine stains from your paneling using supplies found in the home.
Fill a 1-gallon bucket halfway with hot water and add 1 cup of white vinegar. Stir in 1/2 cup baking soda and allow the mixture to foam. The foam is a natural chemical reaction between the vinegar and baking soda and is not harmful. This creates a grease-cutting, nicotine stain remover.
Dip your scrub brush in the cleansing solution and scrub your paneling. Move the scrub brush with the grain of the paneling, if it has a grain. When the cleansing solution looks dirty, empty it out and make a fresh batch.
Repeat step 2 on all the paneling if the smoking stains are old. Most types of paneling are porous, and the nicotine stains may be absorbed into the pores of the paneling. To ensure that you've removed all the nicotine stains, wash the paneling with the grease-cutting cleanser until the wash water stays clean.
Rinse your walls to remove the baking soda by wiping them down with a clean cloth dampened with plain water. If, during the rinsing process, any nicotine stain transfers to your rinsing cloth, then wash that area with the baking soda and vinegar solution again before rinsing. Complete removal of the nicotine stains will ensure that you've removed the cigarette odor as well.
Dry your walls with a clean cloth. Open a window to help with the process and get some fresh air in the room.