The woman escaped the attack Thursday without major injuries, The Guardian reported.
She told police she was pushing her baby in a stroller through an underpass in Salford, Greater Manchester, when the man came up from behind, made sexual and racist remarks and then threw a corrosive liquid at her back and chest, The Sun said.
"You've got dark skin -- I can do something about that," he was quoted as saying.
Passersby summoned help and she was treated for burns.
Police released a sketch of the suspect based on the woman's description, the Guardian said.
"She received nasty burns to the chest and back but fortunately the injuries were not as bad as they could have been, and her baby was thankfully unhurt. She has been very brave and was able to give us a very good description of her attacker."