The production of phosphazene polymers represented by the general formula ##STR1## WHEREIN N IS AN INTEGER FROM 7 TO UPWARDS OF 50,000 WHEREIN ONE OR MORE KINDS OF OR or OR' groups is attached to the phosphorus atoms in a substantially linear chain of alternating P and N atoms, the groups when more than one group is present being randomly distributed along the PN backbone, is enhanced by employing a single solvent for both each of the reactants (polydihalophosphazene and either aryloxide and/or alkoxide) and for the product (phosphazene polymer). By this expedient, the formation of the desired product is achieved in a homogeneous system rather than in a heterogeneous system as in the prior art where different solvents were employed for each of the reactants and for the reaction products.