The family of Jordan McLachlan, 26, who volunteered to help Ukraine after Russia's invasion in February 2022, said he died on Friday while serving on the front line, the BBC reported.
The statement said: "Jordan always believed he was doing something meaningful, and we are all proud of him for helping others".
McLachlan's family said he joined the Ukrainian army shortly after volunteering three years ago.
They said they were awaiting further information from the British Foreign Office, as information about how the fatal outcome came to be is currently very limited.
A spokesman for The Foreign Office said: "We support the family of a British man who died in Ukraine and are in contact with the local authorities."
The BBC recalls that in December 2022, another Scottish volunteer, Jonathan Shenkin from Glasgow, died in Ukraine.