Guided wave technology has been successfully implemented in the field of NDT as a defect screening technique for many years now, however, there is increasing interest in their use as a method of corrosion monitoring over larger areas. The dispersion characteristics of some guided wave modes means that their velocity is dependent on the thickness of the material in which they are propagating, therefore a change in thickness of the component under test will result in a change in the arrival time of the wave. This projects has evaluated the suitability of using shear horizontal waves for the purposes of extracting the average thickness of a plate along a line between two transducers. The work concentrates on a method for extracting a temperature compensated thickness value from measured SH guided wave signals.