The solubility, at 25°C, of calcium citrate, Ca[SUB3](C[SUB6]H[SUB5]O[SUB7])[SUB2]. 4H[SUB2]0, in NaC1O[SUB4] solutions in the molality (m) range 0-3.5, has been determined by potentiometric titration with EDTA, using the Hg[SUP2+]/Hg half-cell. The increase of solubility with m has been explained with the specific interaction theory by assuming, for Ca[SUB3](C[SUB6]H[SUB5]O[SUB7])2.4H[SUB2]O(s) ⇄ 3Ca[SUP2+] +2C[SUB6]H[SUB5]O[SUP3-,SUB7], log K[SUBs0] = -17.81± 0.03 and the interaction coefficient between Na[SUP+] and C[SUB6]H[SUB5]O[SUP3-,SUB7] ions equal to 0.08 ± 0.03 -(0.06 ± 0.01)m. This coefficient allows the extrapolation to the infinite dilution reference state of stability constants determined in concentrated ionic media. Results of calculations compare well with those of the literature. [ABSTRACT FROM AUTHOR]