The 25-year-old allegedly doused his mother in gasoline and set her on fire on Wednesday morning.
The 51-year-old woman herself called police in the German state of Saxony at 4 am, but was found dead less than 10 minutes later in her home, a Görlitz police spokesperson said.
The woman's son was arrested near the crime scene, and he is being investigated for the crime. Officials have not announced whether they have a warrant for the man's arrest.
The motive for the crime remains unclear. It is also unclear whether the woman's son lived with her or had a job. Police are searching for other family members to help clarify the situation.