Has an acyl-CoA thioesterase activity with a preference for the long chain fatty acyl-CoA thioesters hexadecanoyl-CoA/palmitoyl-CoA and tetradecanoyl-CoA/myristoyl-CoA which are the main substrates in the mitochondrial beta-oxidation pathway. H2O + hexadecanoyl-CoA = CoA + H(+) + hexadecanoate H2O + tetradecanoyl-CoA = CoA + H(+) + tetradecanoate dodecanoyl-CoA + H2O = CoA + dodecanoate + H(+) butanoyl-CoA + H2O = butanoate + CoA + H(+) kcat is 5 min(-1) for the hydrolysis of hexadecanoyl-CoA (PubMed:22897136). kcat is 3.5 min(-1) for the hydrolysis of tetradecanoyl-CoA (PubMed:22897136). kcat is 2.3 min(-1) for the hydrolysis of dodecanoyl-CoA (PubMed:22897136). kcat is 0.2 min(-1) for the hydrolysis of butanoyl-CoA (PubMed:22897136). Lipid metabolism; fatty acid metabolism. Isoform 1 is predominantly expressed in skeletal muscle, liver, testis, stomach, spleen, lung and brain. Isoform 2 is predominantly expressed in kidney, uterus, hibernoma and white adipose tissue. By cold exposure and repressed by heat exposure.