The solubilities and the refractive indexes of saturated solns. of the title system at 30?have been studied and the corresponding equilibrium diagram and refractive index diagram were constructed. Both solubility curve and refractive index curve of the system consist of three branches, corresponding to 4-acetylantipyrine (ACAP), Sm(ACAP)2(NO3)3 and Sm(NO3)3?H2O resp. The Sm(ACAP)2(NO3)3 is a new compound It was characterized by chem. and elemental anal., IR spectra, TG-DTG and molar conductivity (in DMF). The influences of the anion on the interaction between the ACAP and the rare earth ion has been discussed briefly.

Key words: PHASE EQUILIBRIUM, INFRARED SPECTROPHOTOMETRY, WATER, ELEMENTAL ANALYSIS, TERNARY SYSTEM, NITRATE, THERMOGRAVIMETRY, SAMARIUM COMPLEX, SAMARIC NITRATE