In this paper we review the new chemical species of magnecules introduced in preceding works (see monograph, R.M. Santilli, Foundations of hadronic chemistry with applications to new clean energies and fuels. Boston-Dordrecht-London: Kluwer Academic Publisher, 2001 for a general review), which consist of individual atoms, radicals and ordinary molecules bonded together into stable clusters under a new internal attractive force originating from the toroidal polarization of the orbitals of atomic electrons under strong external magnetic fields. We then introduce, apparently for the first time, the hypothesis of new chemical species of hydrogen, oxygen and other gases with magnecular structure called MagneHydrogen(TM), MagneOxygen(TM), etc. or MagneH(TM), MagneO(TM), etc. for short (international patents pending). We then present the experimental evidence according to which the latter gases possess specific weight and energy content greater than the corresponding values of the same gases with conventional molecular structure. We show that the use of MagneH and MagneO in fuel cells implies: (1) an increase of fuel cells voltage, power and efficiency; (2) a decrease of storage volumes; and (3) a significant decrease in operating costs. The equipment for the industrial production of MagneH and MagneO is identified. We also study a particular form of MagneH with specific weight of about 7 times that of the hydrogen which is particularly suited for use as fuel in internal combustion engines, and show that such a new species implies: (i) the elimination of liquefaction of conventional hydrogen as currently used by BMW, GM, and other car manufacturers; (ii) performance essentially equivalent to that of the same engine when operating on gasoline; and (iii) the achievement of cost competitiveness of MagneH with respect to fossil fuels, of course, when produced in sufficiently large volumes. We also indicate that the liquefaction of MagneH and MagneO is predicted to cost significantly less than ordinary gases (in view of a mutual attraction among magnetically polarized magnecules which does not exist in conventional gases), and that their use as fuel for rocket propulsion is expected to imply a significant increase of the payload, or a corresponding decrease of boosters weight. All the above advances are dependent on the features of the selected equipment for the production of MagneH and MagneO (including electric power, pressure, etc.), as well as the duration of the processing. The paper ends with the indication of other applications of the new chemical species, the solicitation of independent experimental verifications, and the identification of new intriguing open problems. 0 2002 International Association for Hydrogen Energy. Published by Elsevier Science Ltd. All rights reserved.