A new trend in flame- and heat-resistant polymers is the modification of organic by-products such as lignins. Here we continue a discussion of lignin modification; in particular, the reaction of lignosulfonates with chlorophosphazenes. The reactivity of Borregaard-type lignosulfonates toward chlorophosphazenes was studied. The properties of the products obtained, especially their flame and heat resistance, as well as SEM data, were investigated.