This paper reports the fabrication and application of a microfluidic Lab-on-a-Chip platform to study the electrotactic movements of pathogenic microorganisms. The movement of the pathogens in response to electric fields are one way in which they are thought to locate their hosts. Design and fabrication of the platform, and associated micro-electronics are described. The platform contains arrays of micro-electrodes that generate an electric field of defined strength in a micro-chamber into which feed inlet and outlet channels for entry and exit of media and microorganisms. To demonstrate applicability of the platform, motile zoospores of the pathogenic oomycete Phytophthora nicotianae were seeded in the inlet and a voltage was applied to investigate the electrotactic responses of the zoospores. This platform offers a unique opportunity to study electrotactic movements that may be responsible for the ability of the pathogens to locate and invade host tissue.