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In this study, mullitisation at low temperature was observed in an oxime-modified aluminosiloxane precursor [(CH3)2CNO}2Al{OSi(Ph)2O}Al{ONC(CH3)2}2]. Oxime-modified aluminosiloxane was synthesised by carrying out a reaction between oxime-modified aluminium(III) isopropoxide [{(CH3)2CNO}2Al(OiPr)] and diphenylsilanediol in a 2:1 molar ratio. 29Si and 27Al NMR spectroscopic data suggest the presence of tetra- and penta-coordinated environment around Si and Al elements. The presence of Al-O-Si linkages was observed in the FTIR spectra of the precursor as well as in the formed mullite. Thermal study of precursor suggests clean decomposition of precursor molecules to amorphous aluminosilicate 3Al2O.2SiO2at ~500°C. Low temperature (900°C) transformation of precursor to mullite was observed by the sol-gel process. XRD (X-ray diffraction) and FTIR (Fourier Transform Infrared) studies suggest the formation of mullite in the orthorhombic phase without phase segregation. Scanning electron microscopy suggests agglomeration of nanocrystallite, while HRTEM (High Resolution Transmission Electron Microscopy) results corroborate with the XRD data. [ABSTRACT FROM AUTHOR]