A topochemical route to nondefect, three-dimensional perovskites from lamellar Dion-Jacobson and Ruddlesden-Popper precursors was demonstrated. The method involves reduction of one of the ions (in this case Eu3+) in the precursor phase and concomitant loss of oxygen. CsEu2Ti2NbO10, a three-layer Dion-Jacobson compound, was ion-exchanged to AEu(2)Ti(2)NbO(10) (A = Na, Li) and reduced in hydrogen to form the SrTiO3-type perovskites AEu(2)Ti(2)NbO(9). Similarly, K2Eu2Ti3O10, a three-layer Ruddlesden-Popper compound, underwent divalent ion exchange to form the Dion-Jacobson compounds A(II)Eu(2)Ti(3)O(10) (A(II) = Ca, Sr) and (MEu2Ti3O10)-Eu-II (MII = Ni, CU, Zn), which were reduced in hydrogen to perovskite-type A(II)Eu(2)Ti(3)O(9) and M-II- Eu2Ti3O9, respectively. The A(II) and Eu2+ ions of A(II)Eu(2)Ti(3)O(9) remain ordered, while A-site disordering occurs in the other perovskites. In all cases, the anisotropic texture of the layered precursors is retained in the product perovskite phase.