Mount Decoeli is a 2,332-metre (7,651-foot) pyramidal peak located in the Kluane Ranges of the Saint Elias Mountains in Yukon, Canada.

Its nearest higher peak is Mount Archibald, 6 km (3.7 mi) to the south.

[2] James J. McArthur was a Canadian surveyor and mountaineer who undertook extensive surveying in the Yukon during his later years.

In 1908 he made the first ascent of Williams Peak accompanied by Edmond Treau de Coeli (1873–1963).

Precipitation runoff from the peak and meltwater from its rock glacier drains into tributaries of the Kaskawulsh River.