Robbers sprayed bleach at a man and his dog in the street before stealing his £50 watch, say police.
The 34 year-old victim was taking his pet for a walk in Silver Link Road in Tamworth, Staffordshire, when he was confronted by three men wearing black hooded tops.
"One of the men sprayed liquid at the victim's dog and then in his face," said a spokesperson for Staffordshire Police.
"The men stole his watch, worth £50 and ran off towards the grassed area on the same road."
The victim was treated at the scene near the junction with Collett before being taken to hospital, though his injuries are described by police as "not life-altering".
His dog is being treated at the RSPCA Birmingham Animal Centre and Hospital.
Attacks using corrosive liquids appear to have been increasing in recent years.
Last weekend a three-year old boy suffered serious burns to his face and arm in an acid attack at a Home Bargains store in Worcester.
The child's father and five other men have all been charged with conspiracy to commit grievous bodily harm.
On Tuesday a woman suffered chemical burns to her face after a substance was thrown at her in Birmingham.
Anyone who may have information about the incident in Tamworth is asked to call Staffordshire Police on 101 or Crimestoppers anonymously on 0800 555111.