Sterilizing heat-sensitive containers by introducing hydrogen peroxide into a container and activating it with an activating medium comprises heating the activating medium to a temperature above a limiting temperature of the container and injecting into the container in pulses. An independent claim is also included for a sterilizer for treating containers by introducing hydrogen peroxide into a container and activating it with an activating medium, comprising a heating channel for heating the activating medium to a treatment temperature and a valve control system for delivery of the hot activating medium through a delivery opening into the inside of the container, the valve control system comprising a valve system and an actuator for pulsed opening of the valve system.
