David Dixon, 53, who was missing since Tuesday's bombings, has been confirmed dead by his family.
Tuesday's attacks on the Brussels airport and metro system killed 31 people and injured many more.
A British man, thought to have been on the metro system at the time of the Brussels attacks, has been reported missing by friends on social media.
His partner Charlotte Sutcliffe and other friends say that David Dixon, originally from Hartlepool, did not arrive in his office on Tuesday morning in the Belgian capital.
A post on Facebook by Rachel Stevenson said he has not made contact with his partner since leaving for work in the morning.
Ms Sutcliffe is carrying out a "heartbreaking" search of Brussels' hospitals, according to her sister Marie.
"Understandably she is very, very distressed," she told BBC Radio Four.
"Not everybody has been identified yet, of the injured, so it's waiting for that process to happen. Everybody is struggling with communication there, or they were yesterday, with phones being down and there being a lockdown".
Other appeals featuring a picture of Mr Dixon with Ms Sutcliffe were shared on Twitter.
An American survivor of the Brussels airport bombing - who also survived the Boston bombing - has recounted the deadly attack.
A British woman captured in amateur footage huddling with her family after the Brussels airport blasts has spoken of her ordeal.
After escaping the Brussels Airport suicide attacks, Sneha Mehta wrote an inspirational message of hope and peace for her unborn child.