High voltage square pulse generators, with fall times of 1 μs and 45 ns have been fabricated for the measurement of electro-optic Kerr relaxation studies in macromolecules. These have been fabricated with a pulse forming network in the Blumlein line configuration with discrete components. The switching is brought about by high voltage spark gaps, instead of the thyratrons and silicon controlled rectifiers (SCRs), which have voltage limitations. The performance of these pulse generators are found to be consistent and stable, without any change in the pulse shape even at very high voltages and repetition rates. The Kerr constants and relaxation times measured with these pulse generators for the liquid crystal p-(methoxybenzelidene)-p-butylaniline (MBBA) at its nematic to isotropic phase transition temperature (43.5°C) are found to be in very good agreement with the reported values obtained from the optical Kerr effect investigations using high power Q-switched solid state lasers.