A new family Thermoarcturidae of valviferan isopod is erected for three genera, Califarcturus n. gen., Spinarcturus Kensley, 1978 and Thermoarcturus Paul & Menzies, 1971, each represented by one species. All share strong stiff setae on distal articles of pereopods 2-4, uropods with two rami, and a tomentum of fine setae over the cuticle. The members are distinguished from Antarcturidae, Arcturididae, Rectarcturidae and Arcturidae, similar arcturoid families that differ in having rows of filter setae on pereopods 2-4 and usually lack one or more uropodal rami.