This paper presents an investigation of semiconductor switches for high voltage solid-state pulsed power modulators from the viewpoint of pulse rising time, efficiency, and reliability. A comparative study of insulated gate bipolar transistor (IGBT) and metal oxide semiconductor field effect transistor (MOSFET) devices is provided, focusing particularly on the characteristics of each device for pulsed power applications. Two kinds of stacks for 10-kV pulses are developed with a high voltage capacitor charger in order to experimentally compare the characteristics of each device. Although the structure of each stack is similar, the number of power cells for the 10-kV pulse is different due to the device voltage rating. The power cell voltage for IGBT and MOSFET-based stacks is about 840 V and 560 V, respectively. Therefore, two types of transformer, with six secondary windings for the IGBT stack and nine secondary windings for the MOSFET stack, are also designed for storage capacitor charging. Moreover, the ease of varying the pulse repetition rate and the pulse width shows the advantages of the developed modulators in facilitating the measurement of device characteristics in different pulse output conditions. The experiments are performed with noninductive resistor loads, and the results of the comparison tests are discussed. In addition, the results prove that the developed modulator can be effectively used for high repetitive pulsed power applications.