Speaking after talks with Kosovo Prime Minister Thaci in Pristina, Hague said "dialogue between Serbia and Kosovo on normalising relations is essential for both countries as they move towards EU integration."
A new chapter in EU-Kosovo relations is opening, which "is enormously positive for Kosovo," but it will "require hard work and fundamental reforms in areas such as the economy, rule of law, the fight against corruption, electoral reform and public administration," said Hague.
"The path to EU membership is rewarding, but it is not necessarily quick or easy. It will take sustained and hard work," he said, adding that "Kosovo can count on UK support as it takes forward work in key areas such as rule of law, corruption and minority rights."
Thaci said one should be realistic and not expect Serbia to recognise the independence Kosovo declared in 2008 in a matter of days, weeks or months, Agence France-Presse reported.
But the dialogue will build better relations between Belgrade and Pristina, eventually resulting in recognition, said Thaci.
Hague also met with Kosovo President Atifete Jahjaga. He said EU enlargement in Southeast Europe included Kosovo and that there was no changing of borders in the Balkans.
Jahjaga said she supported a meeting held between Thaci and Serbian PM Ivica Dacic as well as meetings between the most senior Kosovo and Serbian officials announced for mid-November.
Later today, Hague will meet with Serbian President Tomislav Nikolic in Belgrade.