Bioavailability of Coenzyme-Q 10 ("Co-Q10"), an oil-soluble substance, can be enhanced in a subject by modifying, e.g. nanonizing or charging, the form of Co-Q10. Co-Q10 bioavailability also can be enhanced by administering Co-Q10 to the subject as an oil (lipid)-based and water (hydro)-based mixed composition, along with other optional components, such as oils, resins and other carriers. Accordingly, the invention provides various Co-Q10 compositions, e.g. compositions comprised of (i) Co-Q10 dissolved in one or more Co-Q10-soluble oils and (ii) Co-Q10 in admixture with at least one water-dispersible agent. A Co-Q10 complex of the invention, therefore, yields an increased cell absorption rate, as well as an enhanced percentage of Co-Q10 peak absorption, compared to previously known compounds. Methods for making and using the aforementioned compositions also are provided.