The brother of a Quebec woman who was attacked with acid during a conjugal dispute Sunday says he wants the courts to treat her assailant harshly.

Tanya St-Arnauld, of the Montreal suburb of Longueuil, is in a medically induced coma with serious burns to her upper body after she had a corrosive liquid thrown on her .

According to Martin Simard of the Longueuil police, St-Arnauld, 29, has burns to 70 per cent of her body caused by a household cleaning product like drain or cement cleaner.

Her boyfriend, 27-year-old Nikolas Stefanatos of Brossard, Que., has been charged with aggravated assault in the case. His bail hearing was put over at his first court appearance on Monday.

Nikolas Stefanatos, 27, has been charged with aggravated assault. (Facebook)

Simard said police were called to the woman's apartment on Ste-Catherine Street in Longueuil around 5 a.m. Sunday.

The woman's brother, Maxime Gosselin, 23, was away camping when he received a call from St-Arnauld's friend. She told Gosselin something had happened to his sister.

According to St-Arnauld's friend, the woman was sprayed with ketchup and mustard during a fight. She left to talk to a friend and when she returned, she was splashed with a corrosive product.

"She was suffering, she was yelling," Gosselin said. "They saw her skin literally melt off."

Tanya St Arnauld is in a medically induced coma while she recovers from her burns. (Maxime Gosselin)

The paint on the apartment wall near the scene bubbled and peeled off from being sprayed with the product.

Gosselin said he "couldn't believe it," but that he was aware Stefanatos and St-Arnauld had a volatile relationship.

"I didn't know something this bad was going to happen, but a week earlier they had some complications and he took away her key in the middle of the parking lot at a hardware store and left her there for six hours. I went there to see if she was OK and she was full of juice, her car was full of it."

Gosselin said his sister told him Stefanatos has doused her in orange juice before leaving her stranded.

St-Arnauld asked her brother to stay in her apartment while she showered in case Stefanatos came back to the apartment.

"She didn't want to be in the shower and be alone if he came in," Gosselin said.

He added that he hopes "justice will take its course" and his sister's attacker will receive a tough sentence.

"I don't want him like six months and he's out. It's not going to fix my sister. She's going to be like that for life. She's going to have some scars for sure," he said.

According to court files, Stefanatos was found guilty of assault in 2006 and sentenced to two years of supervised probation. He was expected back in court on Sept. 10 for failing to comply with probation orders.