The temperature of the grill should be around 300 F to 500 F.
Place the chicken on the grill and let it cook for 3 to 5 minutes or until you see grill marks and then flip the chicken over again and let it cook on the other side for another 3 to 5 minutes and keep doing this every 5 minutes at least and after 20 to 25 minutes on the grill the chicken should be fully cooked and ready to eat.
Use a meat thermometer and place the meat thermometer in the thickest part of the chicken and check to see if the chicken has reached a minimum of 165 F for the internal temperature of the chicken.
If it's reached 165 F on the internal temperature then the chicken is fully cooked.