The negative temperature coefficient of resistivity (TCR) displayed by p-Ta, which has thus far not been satisfactorily explained, has been examined by measuring the variation of electrical resistivity with temperature, from -2S300 OK, and by measuring the Hall coefficients, at room temperature and a t 77 OK, of films containing up to -60 at.% oxygen. The Hall measurements indicate carrier concentrations of -loz2 ~m -~ and mobilities of -1 cm2/V s. The analysis of the results has considered the granular structure of the films and has subsequently compared these results with an 'activated tunneling' model of conduction. Theoretical calculations which assume the film to be comprised of cubic grains separated by T a 2 0 5 agree well with the experimental measurements.Metallic conduction still appears to be contributing to the film properties even at the highest oxygen concentrations of the present investigation.Le coefficient negatif de variation de resistivite en fonction de la temperature (TCR) du p-Ta, qui n'a pas encore ete expliquk de f a~o n satisfaisante, a etC examine en mesurant la resistivite Clectrique en fonction de la temperature de 20 a 300 "K et en mesurant, a temperature ambiante et a 77 OK, les coefficients de Hall de films contenant jusqu'a 60% d'oxygene atomique. Les mesures d'effet Hall indiquent des concentrations de porteurs de cm-3 et des mobilites de -1 cm2/V s. Lors de I'analyse des resultats on a tenu compte de la structure granulaire des films et on a subsequemment compare ces resultats avec un modele "d'effet tunnel active" de la conduction. Des calculs theoriques, faits en supposant que le film est compose de grains cubiques sCparCs par Ta205, concordent tres bien avec les mesures expirimentales.La conduction metallique contribue aux proprietes du film mCme avec les plus fortes concentrations en oxygene utilisees au cours de cette investigation.