Zhang Jike beat compatriot Wang Hao 4-1 in an all-Chinese men's singles table tennis final.
18-16 11-5 11-6 10-12 13-11 as Wang suffered a third successive defeat in an Olympic final.
Zhang dominated as China took their second table tennis gold at London 2012 after
Li Xiaoxia's win over team-mate Ding Ning
in the women's final.
Germany's Dimitrij Ovtcharov beat Chih-Yuan Chuang of Chinese Taepei to win bronze at the ExCeL.
Jike celebrated victory by kissing the podium and then holding aloft the Chinese flag.