The woman, Bangorn Prangchaikul, lived alone in the house. Her body was found in the bathroom.
Her relatives said she had chronic aliments and could barely move.
The fire started at 6.10pm in a community behind Surin provincial hall.
Firefighters managed to prevent the blaze from spreading to other houses but the woman's house was destroyed.
Surin governor Atthaporn Singhawichai assisted at the scene.
The cause of the fire has yet to be determined.