The observation of Internal Transport Barriers (ITBs) in which ion thermal diffusivity is reduced to its neo-classical level has been made for the first time in tokamak plasmas fuelled with deuterium and tritium (DT) ions using a broad or hollow current density profile. The heating and the current profile required to obtain an ITB are similar in D-T and in D-D plasmas. Central ion temperatures close to 40keV, ion temperature gradients of 150keV/m and plasma pressure gradients of 106Pa/m were observed in DT leading to a fusion triple product niTiτE=1.1021 m-3keVs and 8.2MW of fusion power. There is potential for further optimisation which may prove to be an important step towards the development of efficient tokamak fusion reactors.