a1 Université de Toulouse, C.U.F.R. J.-F. Champollion, and I.M.T. (Institut de Mathématiques de Toulouse UMR CNRS n° 5219), Campus d'Albi, Place de Verdun, 81012 Albi Cedex, France. email@example.com
A new model of smooth K0-theory ( ) is constructed, with the help of the total Chern class (contrary to the theories considered in ]1], ,  and  which use the Chern character). The correspondence with the earlier model  is obtained by adapting, at the level of transgression forms, the usual formulae which express the Chern character in terms of the Chern classes and vice versa.
The advantage of this new model is that it allows constructing Chern classes with values in integral Chern-Simons characters in a natural way: this construction answers a question asked by U. Bunke .
(Received July 19 2008)