Major phases mullites prepared by hydrothermal crystallization method with kaolinite as raw material, were composite nanocrystals. The matter phases, grain size and thermal stability of composite nanocrystals made in different condition were characterized by XRD, TEM, BET and TG-DTA. Major phases nanocrystals were studied in Temperature Programmed Desorption of CO, SO2, and supported Ni, Co, and Mn were measured in Temperature Programmed Reduction(TPR). The CO2 and solid sulfur were found in adsorption preduts. It was showed that adsorbates have changed on the surface of the nanocrystals. Due to different particle sizes of micro-metre scales crystals and nanocrystals of the supported Ni, Co and Mn, peak temperature and area differed along with the different interaction between supported oxides and the support. It was showed that there was structural effect between the supported oxides of Ni, Co, Mn and the supporter. Moreover, structural difference in the surface of crystals led to different comsumption of H2.