The basic transmission characteristics of power cables, such as attenuation and surge impedance as functions of frequency, are required as data for transient analysis and for the interpretation of h.v.-surge recordings. Measurements of capacitance, inductance and associated dielectric andI2Rlosses for sample lengths of 132 kV power cable have been carried out over a wide frequency range from 50 Hz to 800 kHz. The results concerning the main cable insulation at ambient temperature are shown in graphs of tan δ and the percentage variation in capacitance against the logarithm of frequency. The influences of skin effect are shown in graphs of inductance and series resistance against frequency for a short-circuited cable; they are, at least for a range of ultra-audio frequencies, broadly as might be predicted on the basis of conventional ‘skin-depth’ theory. From the measured quantities, characteristic impedances and attenuation coefficients have been calculated and presented graphically; a step-voltage test yielded a surge impedance in agreement with that calculated for a frequency of 1 MHz. The cable samples were wrapped with metal tape, and the capacitance and tan δ measurements were carried out between the cable (outer) screen and the metal tape. Results concerning the neoprene and hessian serving (required for idealised studies concerning propagation in the sheath-earth mode) are presented in graphs similar to those for the main insulation. The variation with temperature of the effective permittivity and tan δ of the impregnated-paper insulation, obtained by heating the core of the cable to simulate the cable loss at full rating, is also given with the relevant thermal measurements.