Police arrested the 21-year-old last night on suspicion of causing criminal damage and he is being questioned at Trinity Road police station today.
Yesterday, the Polski Sklep shop in Gilda Parade, Whitchurch, was sealed off and police were guarding it after it was subjected to the attack on Tuesday.
Three people were treated in a decontamination unit after a chemical was thrown in through the door at 5.40pm. Staff reported having breathing difficulties after the attack.
An investigation by Avon Fire and Rescue Service found the substance involved was butanoic acid, which is foul-smelling but non-toxic.
The staff were given showers in a mobile decontamination unit brought to the scene by firefighters, but paramedics found they had suffered no injuries and did not need medical treatment.