Fructose 1,6-bisphosphatase [EC. 3.1.3.11] is activated by the treatment with 0.1 mM cystamine up to about 400% compared to its original activity (dithiothreitol-reduced form). Thiol compounds (0.1 mM of cysteamine and dithiothreitol) can restore its activity effectively. Reduced glutathione, at 0.2 mM, also restores fructose 1,6-bisphosphatase activity only in the presence of cystamine. When excess cystamine is removed, the addition of 1.0 U/ml thioltransferase is able to restore FBPase activity very efficiently coexistence with 0.2 mM reduced glutathione though reduced glutathione alone does not work.