We have designed a novel positron emission tomography (PET) radiotracer, [11C]-ThioABP, a thiazole based derivative for imaging the metabotropic glutamate receptor subtype 5 (mGluR5), and prepared the hydroxy oxime precursor 4 in a 15% overall yield. [11C]-ThioABP was radiosynthesized in the Veenstra module and obtained in a decay corrected radiochemical yield of 40% and specific activity of 80–250 GBq μmol−1 at the end of synthesis. ThioABP exhibited excellent binding affinity (Ki) in vitro of 1.9 ± 0.9 nM and [11C]-ThioABP showed an optimal log D7.4 of 2.4. The autoradiographic studies on rat brain slices revealed specific binding to mGluR5. In vivo evaluation of [11C]-ThioABP including a displacement study with MMPEP in a dynamic PET scan showed a specificity of [11C]-ThioABP for mGluR5. Radio-TLC metabolite studies showed a good metabolic stability of [11C]-ThioABP in vivo. The comparison of biological properties of [11C]-ThioABP and [11C]-ABP688 revealed similarity between these two compounds.