A microemulsion preconcentrate (I), comprises a ubiquinone solubilised in a mixture of a triglyceride with an omega-9 fatty acid and/or omega-6 fatty acid and a surface active component. A microemulsion preconcentrate (I), comprises: (A) a mixture of a triglyceride, especially a medium chain triglyceride, and an omega-9 fatty acid and/or omega-6 fatty acid; (B) a surface active component containing a surfactant, especially a polyoxyethylene surfactant; and (C) a ubiquinone which is soluble in (A) and/or (B). Independent claims are also included for: (1) Microemulsion (II) obtained by admixture of (I) with water or an aqueous medium; and (2) Shaped oral dosage unit containing (I)..