Costa Mesa Police Sgt. Clint Dieball says the man walked into the salon, doused himself with a flammable liquid and set fire to himself just after noon Sunday.
Someone inside the salon doused the flames with a fire extinguisher.
Dieball says the man was burned but alive when paramedics took him to a hospital. Investigators have not determined a motive. Dieball says the man's wife or girlfriend was inside the salon at the time, and the couple had been estranged.
Nobody else was hurt. The salon, Creative Nails & Spa in Costa Mesa, sustained minor fire damage.