Donald Nicholson, 93, from Tyne and Wear, lost his medals whilst travelling to a memorial event in Lincoln on Friday.
The row of five medals may have been left at a service area near Blyth in Nottinghamshire.
A reward of £350 is being offered for their safe return.
On Friday, organisers of an event marking the unveiling of a memorial spire to Bomber Command crewmen, took to Facebook to appeal for help.
The post was shared more than 2,000 times, with the appeal featuring in national press.
One person on Facebook also offered to replace four of the five medals with a duplicate set belonging to their grandfather.
Mr Nicholson, from Houghton-le-Spring, realised his medals were missing when he arrived to take part in a private ceremony at the memorial site on Canwick Hill, in Lincoln.
The site, which is currently under construction, will eventually become the International Bomber Command Centre.
Nicky Barr, director of the project, said to lose them on such a special day was "heartbreaking".
She said Mr Nicolson was left very distressed and appealed for anyone with information to get in touch.
125,000
Aircrew served in Bomber Command in World War Two
364,514 operational sorties flown
55,573 aircrew killed in action
25,611 killed flying from Lincolnshire
70% of aircrew were killed, taken prisoner or injured
Officials have made a renewed appeal for help finding a set of missing medals belonging to a World War Two Bomber Command veteran.