Rowe & Maw has won its first case for the firm's newly-established international regulation team.
It is advising a consortium of more than 28 Chinese coke exporters, including Tianjin General Nice Coke & Chemicals company, one of the country's biggest coke exporters.
The combined group accounts for about half of the 300,000 tonnes of coke exported to Europe from China every year.
The European Union (EU) is arguing with the People's Republic of China over the volume of its exports of coke, a type of coal used in foundries.
EU producers have formed a consortium, EUCOKE, advised by the Brussels office of Spanish firm Garrigues & Andersen.
EUCOKE has complained to the European Commission's Directorate General for Trade that the Chinese exporters have been dumping coke into Europe.
Cliff Stevenson, Rowe & Maw's chief economist, says the case is particularly sensitive, because of World Trade Organisation membership issues. He says: "The Chinese government has taken a great interest in the case."
Philip Ruttley, Rowe & Maw's head of regulation, says: "This is a major case for the People's Republic and is likely to be one of the most important anti-dumping proceedings of recent years.
"It is particularly gratifying to be winning this level of instructions after only six months of being in operation as a team."