A series of hexacelsians with different compositions were synthesized by thermally induced transformation of a LTA zeolite. Various forms of hexacelsians have been characterized by XRPD, IR, Raman and Si-29 MAS NMR method. The phase transformation alpha ->beta hexacelsian was investigated by DSC method. This phase transformation is sensitive to synthesis conditions, doping and thermal treatment. The peak maximum temperature, Tm, varies from 302 up to 353 degrees C. Heat of transformation changes from 0.42 to 1.77 kJ/mol.