The Tc-99m complex of dimethylglycyl-L-seryl-L-cysteinyl(acm)-glycl-L-threonyl-L-lysyl-L-prolyl-L-prolyl-L-arginine (RP128) is a radiopharmaceutical designed for imaging sites of inflammation. RP128 and its rhenium(V) and technetium(V) oxo complexes were prepared and characterized by HPLC and various spectroscopic techniques. Analysis of RP128 showed that the attachment of the dimethylglycyl-L-seryl-L-cysteinyl-glycine sequence and the coordination of it to a TcO3+ core did in not affect the threonyl-L-lysyl-L-prolyl-L-prolyl-L-arginine (TKPPR) portion of the molecule aqueous solution.