Li2CO3-Na2CO3-K2CO3　molten　salt　mixtures　are　potentially　suitable　for　high　temperature　thermal　energy　storage　in　the　concentrating　solar　power.　We　investigated　the　LiNaK　carbonate　salt　with　hydroxides　of　lithium　(LiOH),　potassium　(KOH),　or　calcium　(Ca(OH)(2))　by　using　differential　scanning　calorimetry　(DSC)　and　X-ray　diffraction　(XRD).　From　the　repeated　heating　DSC　curves,　lower　melting　points　with　excellent　reproducibility　were　found　when　10　wt%　LiOH　or　KOH　was　added　into　40　wt%Li2CO3-20　wt%Na2CO3-40　wt%K2CO3.　Based　on　the　characterization　of　XRD　patterns,　the　molten　eutectic　mixtures　consisted　of　LiKCO3,　LiNaCO3,　and　residual　Li2CO3　when　the　ternary　carbonate　salt　was　heated　at　the　temperature　above　the　melting　point　and　cooled　rapidly.　In　the　system　of　LiNaK　carbonate　salt　with　additives　of　LiOH　or　KOH,　more　LiKCO3　and　LiNaCO3　with　lower　melting　point　can　be　formed　by　substitution　reaction.　Thus,　optimal　molar　ratio　for　the　mixed　molten　salts　with　low　melting　point　could　be　quickly　obtained　by　studying　the　composition　of　the　resulting　eutectic　mixtures.　(C)　2015　Elsevier　B.V.　All　rights　reserved.