A polycrystalline CVD diamond detector was installed at on JET tokamak in order to monitor the time dependent 14MeV neutron emission produced by D-T plasma pulses during the Trace Tritium Experiment (TTE) performed in October 2003. This was the first tentative ever attempted to use a CVD diamond detector as neutron monitor in a tokamak environment. Despite its small active volume, the detector was able to detect the 14MeV neutron emissions (>1.0 × 1015 n/shot) with good reliability and stability during the experimental campaign that lasted five weeks. The comparison with standard silicon detectors presently used at JET as 14MeV neutron monitors is reported, showing excellent correlation between the measurements.The results prove that CVD diamond detectors can be reliably used in a tokamak environment and therefore confirm the potential of this technology for next step machines like ITER.