About 300 degrees F. I sometimes use a kitchen thermometer to check the temperature and sometimes I just insert a wooden toothpick into the oil. If bubbles form around the toothpick, the oil is ready for frying. The trick is to keep the temperature and not let the oil get too hot. When it reaches frying temperature, turn the heat down a little bit. We want to keep the oil hot but not too hot that it burns the fritters from the outside without cooking them from the inside.