NaNO3　and　KNO3　are　frequently-used　molten　salts　as　heat　transfer　media　in　solar　energy　applications.　Experimental　data　of　thermal　conductivity　for　these　salts　and　their　mixtures　from　published　literatures　show　large　discrepancies,　which　lead　to　perplexity　to　the　heat　exchanger　design　in　heat　transfer　process.　In　this　paper,　reliable　data　for　NaNO3　and　KNO3　are　picked　out　based　on　the　experimental　method　and　apparatus　and　correlation.　Then　theoretical　results　of　thermal　conductivity　for　mixtures　of　NaNO3　and　KNO3　are　predicted　with　these　correlations　and　a　previously　developed　theoretical　model.　Comparison　shows　that　theoretical　correlations　predict　the　thermal　conductivity　of　NaNO3　and　KNO3　with　standard　errors　1.77%　and　2.97%　respectively　and　that　theoretical　model　predicts　the　thermal　conductivity　of　NaNO3-KNO3　mixtures　within　standard　error　of　4.15%.　Though　the　latter　error　includes　contributions　due　to　experiment　and　extrapolation　of　correlations　for　NaNO3　and　KNO3　to　the　lower　temperature　range　of　measurement　for　their　binary　mixtures,　the　standard　error　4.15%　has　been　accurate　enough.　It　is　thus　proved　that　correlations　of　NaNO3　and　KNO3　and　the　method　of　predicting　the　thermal　conductivity　of　their　mixtures　in　the　present　work　can　be　used　for　design　of　heat　transfer　system　in　solar　energy　applications.　(C)　2017　The　Authors.　Published　by　Elsevier　Ltd.