Selective　activation　of　saturated　sp(3)　C-H　bonds　to　high-value-added　chemicals　remains　a　significant　but　challenging　task　for　the　sustainable　exploitation　of　available　feedstocks.　However,　the　selective　oxidation　of　C-H　bonds　with　environmentally　benign　oxygen　is　often　very　difficult　to　control.　Research　works　available　in　thermal　heterogeneous　catalysis　often　involve　the　use　of　transition　metal　particles　together　with　harsh　reaction　conditions,　e.g.,　high　temperature　and　high　pressure,　which　results　in　the　difficulty　in　controlling　the　selectivity.　Here,　we　report　a　very　simple　room　temperature　method　to　prepare　a　cubic　phase,　sheet　structured　semiconductor　CdS　sample.　The　as-prepared　CdS　is　able　to　be　used　as　a　visible-light-driven　photocatalyst　for　the　selective　oxidation　of　saturated　primary　C-H　bonds　in　alkyl　aromatics　with　high　activity　and　selectivity　using　molecular　oxygen　as　a　benign　oxidant　and　benzotrifluoride　as　the　solvent　under　ambient　conditions,　i.e.,　room　temperature　and　atmospheric　pressure.　The　superior　photocatalytic　performance　of　CdS　can　be　attributed　to　its　unique　assembly　of　sheet　structure　with　cubic　phase,　high　surface　area　and　efficient　separation　of　photogenerated　charge　carriers.　The　possible　reaction　mechanism　for　the　photocatalytic　selective　oxidation　of　such　C-H　bonds　over　the　CdS　semiconductor　has　also　been　proposed.