Cp*CoIII-catalyzed directed C-H trifluoromethylthiolation using N-trifluoromethylthiodibenzenesulfonimide as an electrophilic SCF3 source is described. 6-Arylpurines, an important structural motif in medicinal chemistry, and 2-phenylpyridines selectively afforded mono-trifluoromethylthiolated products in moderate to good yields using an inexpensive first-row transition metal catalyst.