The present study is devoted to the transformation of conformed ashes to zeolites by hydrothermal synthesis. A wide range of experimental conditions was tested to prepare selectively zeolites with different structures. Four different zeolites were synthesised: Na-P1, analcime, cancrinite and sodalite. Stabilisation of the cancrinite phase was achieved by modification of the silica/alumina ratio of the synthesis mixture. The transformation is not restricted to the external surface of the conformed ashes, on the contrary, different techniques have shown that a homogeneous transformation is produced and its yield does not decrease due to the use of a preconformed material. The main contribution of the proposed method is that the final zeolitic material is already compacted and does not require any conformation step or the use of a binder.