Coenocytic　Pd@CdS　nanocomposite　has　been　successfully　prepared　via　a　facile　wet　chemistry　approach.　Its　structure　and　properties　have　been　characterized　by　a　series　of　techniques,　including　field-emission　scanning　electron　microscopy　(FE-SEM),　transmission　electron　microscopy　(TEM),　energy-dispersive　X-ray　spectroscopy　(EDX),　X-ray　photoelectron　spectroscopy　(XPS),　X-ray　diffraction　(XRD),　ultra-violet/visible　diffuse　reflectance　spectroscopy　(DRS),　nitrogen　adsorption-desorption　and　electron　spin　resonance　spectroscopy　(ESR).　The　results　demonstrate　that　the　Pd　nanoparticles　as　multiple　cores　are　evenly　distributed　inside　the　photoactive　CdS　shell,　forming　a　coenocytic　nanostructure.　It　is　found　that　the　concentration　of　precursors　and　the　intrinsic　nature　of　noble　metal　colloids　play　essential　roles　in　the　growth　process　for　such　noble　metal@semiconductor　nanocomposite.　Accordingly,　a　possible　formation　mechanism　for　the　coenocytic　Pd@CdS　nanocomposite　is　proposed.　The　visible　light　photocatalytic　activity　of　Pd@CdS　has　been　evaluated　by　selective　oxidation　of　a　range　of　alcohols　using　molecular　oxygen　as　oxidant　under　mild　conditions.　The　results　show　that　the　coenocytic　Pd@CdS　exhibits　enhanced　photocatalytic　activity　as　compared　to　blank-CdS　obtained　by　the　same　procedure　in　the　absence　of　Pd　colloid　nanoparticles　as　seeds.　The　enhanced　photocatalytic　performance　of　the　coenocytic　Pd@CdS　can　be　ascribed　to　the　coupling　interaction　of　enhanced　light　absorption　intensity,　the　longer　lifetime　of　photogenerated　charge　carriers　and　its　favorable　adsorptivity.　It　is　expected　that　our　work　could　provide　useful　information　for　fabricating　other　core-shell　nanocomposites　and　open　an　avenue　to　utilizing　them　in　the　field　of　photocatalytic　selective　organic　transformations.　©　2012　The　Royal　Society　of　Chemistry.