MB Roche & Sons Ltd put up the reward on Tuesday after their "err nerr rerd werks" sign was stolen from Hessle Road in the city.
The sign, which apes the city's distinctive accent, known for its rich vowel sounds and dropped Hs, got a lot of positive feedback when it first went up three years ago.
The firm tweeted that "like other iconic pieces of art we have had our infamous road sign stolen from Hessle Road in Hull" .
But sticking to its sense of humour they added that the reward was "one chip buttie".
Director Daniel Roche said he expected the sign which went missing in the last week to be "in some student's living room", adding that whoever wanted it was keen as it had been tie wrapped to one of the guiderails on part of Hessle Road, where the firm has been doing repaving work.
"Hopefully the Hull community will rally round and find it," he added. "It's not going to have left the city."
Hull's accent has been described as having a pronounced guttural quality with many of the sounds coming from "right at the back of the throat" and many of the individual words in the sentences "sort of blending into one".
The 'o' as in hope and no, is pronounced like an ‘er’ in Hull, with 'oh no', becoming 'er ner', and 'phone calls' sounding like “fern curls'.