Gianni Arioli, Hans Koch The critical renormalization fixed point for commuting pairs of area-preserving maps (270K, plain TeX, Section_8.tgz) ABSTRACT. We prove the existence of the critical fixed point (F,G) for MacKay's renormalization operator for pairs of maps of the plane. The maps F and G commute, are area-preserving, reversible, real analytic, and they satisfy a twist condition.