A layered structure is the thermodynamically stable form of the perovskite Ln(2)Ba(2)Cu(2)Ti(2)O(11) (Ln = La) prepared at 1100 degrees C. But contrary to other derivatives with Ln = Nd-Tb variable degrees of order/disorder associated with the concentration of defects can be detected depending on the extension of the synthetic treatments. This oxide was prepared by the ceramic method with varying reaction times. Electron diffraction and HRTEM show the presence of an alpha(p) X alpha(p) X 4 alpha(p) layered perovskite superstructure with a high concentration of defects in samples prepared during 48 h. Longer reaction times (11 days) result in a higher degree of order and a better defined superstructure. For samples reacted during 17 days the order is complete and identical to that found for other related derivatives such as Ln(2)Ba(2)Cu(2)Ti(2)O(11) (Ln = Nd, Eu, Tb).