The influence of divalent salts (MgCl2, CaCl2, BaCl2) on precipitation of polyelectrolyte, poly[(maleic acid)-alt-styrene]sodium salts, NaMA/St, having two degrees of neutralization (100 mass %, 100NaMA/St and 50 mass % 50NaMA/St) from their aqueous solutions, has been investigated. The experiments were performed by variation of the copolymer concentration, c(p) = 0.005-0.04M/L, salt concentration, c(s) = 0.002-0.4M/L, and temperature, T 298-333 K. The critical concentrations of salts, c(sc), used as a measure of solution stability, were determined from turbidimetric measurements, while viscosity and refractive index measurements were used to indicate the changes in dimensions and hydration of polyions, respectively.