Complex forming conditions of 8-hydroxyquinoline with Tc-99m have been specified. (TcO4-)-Tc-99m has been reduced by SnCl2 to a lower oxidation level. Labeling yields have been determined by ITLC (Instant Thin Layer Chromatography). Various parameters, such as pH, temperature, reaction time, ligand to SnCl2 ratio, which can affect the labeling yields, have been determined. Optimum conditions are 4-7 for pH; 15-20 degrees C (room) for temperature; 1.55 for ligand to SnCl2 ratio and 5 min for reaction time.