Captain Voris was the commanding officer of the Vulcan starship Seleya.

Sub-Commander T'Pol served under Captain Voris for a year, as deputy science officer.

This would seem to mean that he was in command at least since 2149, when T'Pol moved to Earth

In December of 2152, his vessel was pulled inside the Delphic Expanse, where it was plagued by spatial anomalies. Attempting to counteract the anomalies, the Seleya began mining in a trellium-D asteroid field, but exposure to the mineral caused Voris and the rest of the crew to go mad.

Voris died in September of 2153 when an Enterprise boarding party overloaded the power grid, destroying the Seleya and all aboard. (ENT: "Impulse")