Pulsed electric fields (PEF) is an innovative non-thermal technology which has attracted considerable interest in the last decades as a valuable and sustainable alternative to conventional techniques in several processes of food industry involving improvement of mass transfer phenomena, liquid food preservation and targeted structural modifications. The first commercial scale applications have been achieved in potato processing industry and fruit juice preservation. However, the full exploitation of PEF technology in food industry requires that the unavoidable electrochemical and chemical reactions accompanying the flow of electric current through the PEF treatment chamber must be minimized, since it may seriously affect food safety and quality, as well as process efficiency, equipment reliability and cost aspects. The occurrence of these reactions is a very complex phenomena, which is affected by several factors, such as circuit topology of the pulse generator, PEF chamber design and electrode material, PEF electrical parameters, as well as composition and chemical-physical properties of the treated products. This chapter describes in detail the electrochemical behavior of a PEF chamber with specific reference to the phenomena that occur at the electrode-solution interface, and explains the main factors controlling the rate and amount of electrochemical reactions. Finally, the main side effects associated to the occurrence of electrochemical and chemical reactions are described, and strategies to eliminate, or at least reduce, the extent of electrochemical phenomena that cause these undesired effects are also suggested.