In this work we calculate the thermopower of Tl2Mn 2O7, together with its static resistivity and dynamical conductivity. This compound exhibits colossal magnetoresistance, which is not adequately explained by the double-exchange mechanism. We use Hubbard operators to reformulate a previous model of Ventura and Alascio that describes the 3d orbitals of Mn with two magnetic configurations, hybridized with a conduction band associated to the Tl. We reformulate a previous treatment to obtain approximate one-electron green's functions (GF) for the model. We have employed these GF to calculate the properties mentioned above for several values of the system parameters and obtained a qualitative agreement with the experimental results. © 2004 Elsevier B.V. All rights reserved.3541-4 SPEC. ISS.3538Ventura, C.I., Alascio, B.R., (1997) Phys. Rev. B, 56, p. 14533Imai, (2000) Phys. Rev. B, 62, p. 12190Shimakawa, Y., (1997) Phys. Rev. B, 55, p. 6399Okamura, (2001) Phys. Rev. B, 64, p. 180409Foglio, M.E., Figueira, M.S., (1999) Phys. Rev. B, 60, p. 11361Foglio, M.E., Figueira, M.S., (2000) Phys. Rev. B, 62, p. 7882Schweitzer, H., Czycholl, G., (1991) Phys. Rev. Lett., 67, p. 3724Foglio, M.E., Barberis, G.E., (2004) J. Magn. Magn. Mat., , Available on-line 13 April 2004