A police helicopter was used as part of the investigation
A woman in her 20s suffered injuries to her face and neck when a "corrosive" liquid was thrown at her.
Part of London Road South, Lowestoft, was cordoned off following the attack shortly before 08:30 BST.
The woman, who has not been named, was taken to hospital for treatment.
A 38-year-old man was arrested at 10:35 after a search involving a police helicopter. Police said the substance was believed to have been of a "corrosive nature".
A Suffolk Police spokesman said: "The area will need to remain cordoned off in order to professionally clear the area of the liquid."
Police sealed off an area following the incident
