To make juicy grilled chicken thighs, it is important to cook them to the right temperature to ensure they are fully cooked and juicy. The internal temperature should reach 74°C when measured with a meat thermometer. To check, insert the thermometer into the thickest part of the thigh, avoiding the bone. Once the temperature reaches 74°C, the meat should be fully cooked and safe to eat. Overcooking can result in dry, tough meat, so monitor the temperature carefully.