The I2zmir–Ankara–Erzincan zone in Turkey is part of the Anatolide belt. In NW Anatolia, near Kütahya, the ophiolitic rocks within the I2zmir–Ankara–Erzincan suture zone have a tholeiitic character and oceanic back-arc chemistry. Amphibolites form a metamorphic sole to part of the ophiolite in the Kütahya region and yield an 40Ar/39Ar age of 93 ± 2 Ma, interpreted to record high-grade metamorphism and intra-oceanic thrusting of pre-existing ocean crust. Gabbros and dykes yield 40Ar/39Ar ages of 94 ± 13 Ma and 48 ± 12 Ma. The first is suggested to be the ophiolite formation age, and the second a regional metamorphic event. The ophiolitic rocks of the Kütahya region are composite and record several events in the evolution of a Neotethyan seaway situated in north–central Anatolia and farther east. They are interpreted to have formed in a small ocean basin marginal to the subducting I2zmir–Ankara–Erzincan ocean. The Kütahya ophiolites of the Anatolide belt are similar in age to the Tauride ophiolites, and the sub-ophiolite metamorphic rocks and dykes in the ultramafic parts of the ophiolites in the Anatolide–Tauride Block formed at the same intraoceanic subduction zone within the same Neotethyan ocean.