This thesis describes work carried out to investigate certain aspects of the performance of a 130 MeV S-band travelling-wave electron linear accelerator and a number of measurement techniques developed in conjunction with these investigations. The series and shunt impedances of the iris-loaded waveguide forming the accelerator structure were accurately measured. The measurement techniques used form three groups: (i) Measurements of operating accelerator performance; (ii) Low power test measurements on individual lengths of the accelerator structure; (iii) Measurements on test pieces of accelerator structure formed into resonant test cavities. A technique of nonresonant perturbation has been particularly developed for high-frequency field measurements and has here been used for group (ii) measurements. Good agreement was obtained between the impedance values measured by the various techniques once certain dimensioning errors of the accelerator structure had been discovered. A technique for the rapid, accurate and very high resolution measurement of the form of the accelerator electron beam bunches has been developed from investigations into the components of the accelerator beam energy 'spectrum. Beam bunch form variation with accelerator operating conditions has been investigated. Measured beam bunch forms are compared with calculated bunch forms expected from the accelerator buncher fields measured by the nonresonant perturbation technique.