The ideal temperature for cooking a pork tenderloin is 375°F. Depending on how you like your pork cooked, temperatures slightly higher or lower can also work. Cooking at 350°F will result in a more tender, juicy pork loin with a slightly pink hue.  On the other hand, if you prefer well-done pork, then cooking at 400°F is more suitable as it will result in a more firm and browned outer layer.  I guess the best temperature to cook a pork tenderloin is 400°F.  It's important to always use a meat thermometer while cooking to ensure that the internal temperature of your pork tenderloin is at least 145°F before serving.