Modelling of lower hybrid current drive with transport calculations is performed with the JETTO transport code which has been upgraded by implementing the Fast Ray-Tracing Code to calculate self-consistent lower hybrid power deposition profiles. Heat and particle transport models that are able to reproduce the experimental JET temperature and density profiles are used in JETTO for predictive high performance modelling. Application of 3.5MW LHCD power provides an inverted q-profile across 50–70 % of the plasma radius whereas without LHCD, the q-profile is monotonic during the flat-top phase. The results predict that the fusion power is about 60% higher for the high performance D-T plasmas in the optimised shear scenario with 3.5MW LHCD applied during the high performance phase than without LHCD at Bt =3.4T and Ip =3.9MA on JET. Also, the width of the ITB is 0.25–0.30m larger and the ITB can be sustained for longer time with LHCD.