Gather the ingredients.
If the salmon is frozen, allow it to defrost in the refrigerator.
Combine the lemon juice, lemon zest, oil, thyme, and garlic in a large resealable bag. Add the salmon and turn the fillets or steaks to coat them evenly.
Seal the bag and refrigerate it for 30 minutes to 1 hour. Do not allow it to marinate any longer as the salmon can become mushy.
Preheat the grill for medium-high heat. Right before placing salmon on the grill, oil the grill grates well using large tongs, folded paper towels, and oil. Make several passes across the grates. This will help the fish from sticking and breaking apart.
Remove the salmon from the bag and place on the hot grill. Brush salmon with marinade from the ziptop bag only once, at the start. Grill the salmon for about 4 to 6 minutes per side.
Remove the salmon from the heat once the internal temperature of the fish reaches 145 F. The salmon should be light in color and flake easily through the thickest part.
Optionally, squeeze fresh lemon over each fillet right before you take it off the grill.
Serve and enjoy!