Police said Roberts, 66, and his wife, 60, got into an argument over money in the 4300-block of North Broadway just after 9 p.m. Sunday.
He allegedly poured rubbing alcohol on his wife and set her on fire with a lighter during the argument, which took place in the alley behind a Salvation Army store.
A witness helped put out the fire by patting down the victim and helping to remove her burning clothing. Roberts' wife is in critical condition at Advocate Illinois Masonic Medical Center with third-degree burns to a large portion of her body.
A police report said during a search, officers found a small plastic bag containing a substance thought to be cannabis in Roberts' prosthetic leg.
Roberts, of the 1400-block of South Canal Street, was arrested and charged with attempted murder in the first degree, aggravated battery with a flammable substance, aggravated battery to a victim age 60 and over and possession of cannabis.
He is due in bond court on Tuesday.
The Sun-Times Media Wire contributed to this report.