Ternary carbonates with a relative low melting point and a high operating temperature is one of the promising heat transfer fluids for Concentrated Solar Power (CSP). In the present work, ternary carbonates nanofluids of K2CO3-Li2CO3-Na2CO3 (4:4:2, mass ratio) with nanoparticles were prepared by using a two step solution method. The specific heat capacity of ternary carbonates nanofluids with different nanoparticles (SiO2, CuO, TiO2, Al2O3) or SiO2 with different size (5, 20, 30, 60 nm) were investigated. The results show that SiO2 nanoparticles are the most effective additive among of the chosen nanoparticles in enhancing the specific heat capacity of ternary carbonates. The enhancement of specific heat capacity of ternary carbonates is 78.0-116.8% in the range of 500-540 degrees C when adding SiO2 in the range of 5-30 nm. The enhancement of specific heat capacity of ternary carbonates nanofluids with CuO, TiO2 and Al2O3 are 50.6-73.9%, 31.1-56.5% and 50.6-66.5% in the range of 500-540 degrees C, respectively. It is proved that there is no chemical reactions between ternary carbonates and the added nanoparticles. The difference in the enhanced specific heat capacity is mainly depended on the dispersive state of nanoparticles and the resulting amount of needle-like nanostructures in ternary carbonates nanofluids.