The　nano-composites　of　whey　protein　hydrolysate　(WPH)　chelated　with　calcium　were　fabricated　in　aqueous　solution　at　30°C　for　20　min,　with　the　ratio　of　hydrolysate　to　calcium　15:1　(w/w).　UV　scanning　spectroscopy,　fluorescent　spectroscopy,　Fourier　transform　infrared　spectroscopy,　dynamic　light　scattering　and　atomic　force　microscopy　were　applied　to　characterize　the　structure　of　the　WPH-calcium　chelate.　The　nano-composites　showed　the　successful　incorporation　of　calcium　into　the　WPH,　indicating　the　interaction　between　calcium　and　WPH.　The　chelation　of　calcium　ions　to　WPH　caused　molecular　folding　and　aggregation　which　led　to　the　formation　of　a　WPH-calcium　chelate　of　nanoparticle　size,　and　the　principal　sites　of　calcium-binding　corresponded　to　the　carboxyl　groups　and　carbonyl　groups　of　WPH.　The　WPH-calcium　chelate　demonstrated　excellent　stability　and　absorbability　under　both　acidic　and　basic　conditions,　which　was　beneficial　for　calcium　absorption　in　the　gastrointestinal　tract　of　the　human　body.　Moreover,　the　calcium　absorption　of　the　WPH-calcium　chelate　on　Caco-2　cells　was　significantly　higher　than　those　of　calcium　gluconate　and　CaCl2in　vitro,　suggesting　the　possible　increase　in　calcium　bioavailability.　The　findings　suggest　that　the　WPH-calcium　chelate　has　the　potential　in　making　dietary　supplements　for　improving　bone　health　of　the　human　body.　©　The　Royal　Society　of　Chemistry　2015.