This mini-review touches on some of the most important aspects of the biochemistry of the second row transition metal, micronutrient, molybdenum (VI) (Mo6+). Molybdenum can exist in metal complexes in a variety of oxidation states ranging from the metallic oxidation state of 0 to the most oxidized form of +6. To date, it is believed that molybdenum is taken up by living cells as the molybdate anion [MoO4]2-. There are not many reviews in the literature that cover the current topic. There are a total of about 50 Mo- Containing Enzymes/Proteins. Alongside the detailed literature review, we are also presenting the reactions of aqueous Mo6+ with the organic ligand Malic Acid (MA). It appeared that, the reaction of Mo6+ with MA in aqueous solutions at 25°C in 0.1 M ionic strength (NaNO3) formed a reaction mixture that released a large number of hydrogen ions, or protons (H+); 17 H+ to be exact. This observation is not surprising for such complex behavior of such complex metal ion in aqueous solutions. This mini-review is a contribution to celebrate the 85th birthday of Professor Mostafa El-Sayed; at department of chemistry of the Georgia Institute of Technology, Atlanta, Georgia, USA.