Green tea does contain caffeine. The content of caffein depends on various factors such as length of brewing time.

Green tea prepared from unfermented leaves contains 30mg of caffeine per 200ml cup, whereas black tea prepared from fully fermented leaves contains 65mg of caffeine per 200ml cup. On the other hand, a cup of instant coffee contains about 60-80 mg of caffeine per 200ml cup. So a cup of green tea has less than half the caffein a cup of coffee has.