A set of new nanoparticles are synthesized in this work at room temperature by combining two oppositely charged non-toxic biopolymer polyelectrolytes in the form of chitosan and lignosulfonate. The influence of factors, such as the intensity of mixing, total solid content, and the reactant ratio on the nanoparticle size, composition, and porosity is investigated using a turbidimeter, dynamic light scattering method, and zeta potential values. A dense hydrophobic core surrounded by a positively charged hydrophilic shell is proposed as a possible structure of the nanoparticles. The interactions between chitosan and lignosulfonate are predominantly governed by the electrostatic forces with a minor role played by hydrogen bonding. The particle size and porosity are seen to increase with an increase of the total solid content while the number of particles is determined from the ratio of the two reactants.