Poly(N-methyl-4-piperidyl methacrylate) (PMPMA) was blended with the lithium or zinc salt of poly(styrenesulfonate) (PSSLi and PSSZn, respectively). PMPMA formed complexes with PSSZn but not with PSSLi in water/ethanol (2:1) solutions, indicating the presence of a strong interaction between PSSZn and PMPMA. PMPMA is immiscible with PSSLi as shown by the appearence of two glass transitions in each blend. Fourier transform infrared spectroscopic measurements showed a shift of the Bohlmann band in all the PMPMA/PSSZn complexes but not in the PMPMA/PSSLi blends. X-ray photoelectron spectroscopic (XPS) studies showed the development of high-binding-energy (BE) N Is peaks in all the PMPMA/PSSZn complexes but not in the PMPMA/PSSLi blends. Interaction between PMPMA and Zn2+ is also evidenced by the development of a low-BE S 2p doublet and a low-BE Zn 2p(3/2) peak in each complex. Therefore, WS reveals the existence of coordination between Zn2+ and PMPMA but not between Lif and PMPMA. The coordination number of Zn2+ is estimated to be 2 from the XPS results. The coordination interaction between Zn2+ and PMPMA is stronger than that between Zn2+ and poly(4-vinylpyridine).