The spectra of small-angle light scattering (SALS) by disperse particles suspended in an absorbing liquid have been numerically simulated using the Mie theory and measured in a wavelength range from 190 to 1100 nm. It is established that the SALS spectra contain regions sensitive to the size and polydispersity of particles with radii ranging from 0.4 to 30 μm. Using the joint processing of SALS and transmission spectra measured using a double-beam spectrophotometer with a modified optical scheme, it is possible to determine the parameters of particles suspended in the absorbing liquid. Data for model suspensions of polystyrene latex particles are presented.