Catalyzes the hydrolysis of acyl-CoAs into free fatty acids and coenzyme A (CoASH), regulating their respective intracellular levels (By similarity). Has acyl-CoA thioesterase activity towards medium (C12) and long-chain (C18) fatty acyl-CoA substrates. Can also hydrolyze 3-hydroxyphenylacetyl-CoA and 3,4-dihydroxyphenylacetyl-CoA (in vitro) (By similarity). May play a role in controlling adaptive thermogenesis (By similarity). a fatty acyl-CoA + H2O = a fatty acid + CoA + H(+) decanoyl-CoA + H2O = CoA + decanoate + H(+) H2O + octanoyl-CoA = CoA + H(+) + octanoate butanoyl-CoA + H2O = butanoate + CoA + H(+) H2O + hexanoyl-CoA = CoA + H(+) + hexanoate H2O + tetradecanoyl-CoA = CoA + H(+) + tetradecanoate H2O + hexadecanoyl-CoA = CoA + H(+) + hexadecanoate dodecanoyl-CoA + H2O = CoA + dodecanoate + H(+) (9Z)-octadecenoyl-CoA + H2O = (9Z)-octadecenoate + CoA + H(+) Homotetramer (By similarity). Interacts with PCTP (By similarity). During interphase, found both in the nucleus and in the cytoplasm. At mitosis, localizes to the spindle. Colocalizes with tubulin. Belongs to the thioesterase PaaI family.