In 2008 he competed in the Middle-East for the first time, taking fifth place and at the high-stakes Ras Al Khaimah Half Marathon with a season's best of 1:00:35. Mogusu won at the Kanto University Track and Field Championships, beating Daniel Gitau and recording a 10,000 metres personal best of 27:27.64 – a championship record and within the Olympic "A" standard for the distance. He did not make the Olympic team but he continued winning on the road racing circuit, leading the Sapporo Half Marathon from the 4 km onwards to take his third victory on the course. He was selected for the Kenyan team at the 2008 IAAF World Half Marathon Championships, but he failed to finish the race in Rio de Janeiro.