Densities (rho, kg m(-3)), and viscosities (eta, 0.1 kg m(-1) s(-1)) of Bovine Serum Albumin (BSA), Egg Albumin and Lysozyme in aqueous iodide salts of lithium, sodium, and potassium, along with cationic surfactant-cetyltrimethyl ammonium bromide (CTAB) were measured at a temperature of 303.15 K. The 0.0010-0.0018 g %, w/v of each protein at an interval of 0.0002 mol L-1 in 0.2, 0.4, and 0.8 millimol L-1 of salt and CTAB are studied. Data are used for apparent molar volumes (V-phi, 10(-6) m(3) mol(-1)) and intrinsic viscosities ([eta], dL kg(-1)), respectively. Data are regressed and extrapolated to zero concentrations for rho(0), eta(0), and V-phi(0) limiting values and S-d, S-n, and S-V corresponding slopes for protein-salt structural interactions. With size of cations, the densities decrease as CTAB > LiI > NaI > KI and increase with salts concentrations, with salts the densities are as Lysozyme > BSA > Egg Albumin, viscosities and V-phi as BSA > Egg-Albumin > Lysozyme. The rho and eta values with CTAB higher and [eta] are lower and converse at around 0.4 mmol L-1 salt and is effective for greater stability of proteins. The [eta] in CTAB are higher than other salts and decreases with size of cations with stronger intermolecular forces. (C) 2008 Wiley Periodicals, Inc. J Appl Polym Sci 110: 2293-2304, 2008