Abstract Five novel N3S pseudo-peptide chelators derived from mercaptoacetic acid have been synthesized and characterized based on the spectroscopic data. All the chelators were labeled with Technicium-99m to evaluate their biological activities. Investigations of their biodistribution in mice showed all five pseudo-peptide chelators (MGQ, MGGQ, MAGQ, MVGQ, MFGQ) are rapidly cleared from blood, mainly through renal clearance. 99mTc- ...