High voltage pulsed field inactivation of Bacillus subtilis and Lactobacillus delbrueckii is demonstrated. A four to five log cycle reduction is achieved in a model food, simulated milk ultrafiltrate (SMUF), with a peak electric field strength of 16 kV/cm and 50 pulses for Bacillus subtilis and with 40 pulses for Lactobacillus delbrueckii; pulse width ranging between 200 and 300 μs. The temperature of the cell suspension was kept below the lethal temperature, demonstrating that inactivation is not due to thermal effects induced by the pulses of high voltage electricity.