Cut and core the apples. You can do this by hand, or if you plan on making lots of dehydrated apples, invest in an apple slicer/corer.
Arrange your apple slices on the dehydrator trays, making sure they are not overlapping as this will prevent even drying of the apples.
Set the temperature of your dehydrator for 130-135 °F and turn it on for about 8 to 10 hours.