While grill is preheating rinse the chicken breast and pat dry with paper towel. Pour grape seed oil over chicken breast. Sprinkle taco seasoning mix over the chicken breast and rub well.
Spray non-stick grill spray on the grates. Place the chicken breast on the grill and cook for 20 minutes on medium-low heat. Flipping halfway through the cooking process.
During the last 3-5 minutes of cooking place the hard corn taco shells on the grill to heat them.
Once the chicken is cooked, remove from the grill and place on a cutting board. Begin chopping the chicken into bit size pieces. Assemble tacos.