The structure of poly(acrylic acid) (PAA), poly(methacrylic acid) (PMAA), and gelatin solutions are studied using the turbidity spectrum and dynamic light scattering methods. The effect of the polymer concentration and pH value of the solutions on the structure and optical properties of polyelectrolyte solutions are investigated. The size of light scattering particles in different systems is calculated. An increase in size was observed with increasing polymer concentration for the PAA solution. The dependence of the particle sizes on concentration is described by a curve with maxima for the PMAA solution. The sizes of the light scattering particles in solutions are compared with data on quality of solvents. The gelation mechanism of gelatin in water solutions was investigated in the wide range of concentration and at different рН values.