Complex heat capacity, C-p* = C'(p) - iC(p)("), of pure glucose and fructose glasses have been investigated by modulated-temperature differential scanning calorimetry (MDSC). According to the linear response theory, real and imaginary parts of complex heat capacity have obtained as a function of temperature through a glass transition. The non-Debye property of thermal relaxation process has examined by means of the Cole-Cole plot. The Cole-Cole plots of two monosaccharide glasses exhibit the non-Debye nature. The results indicate the distribution of relaxation times in fructose is broader than that of glucose. It reflects the broader degree of freedom in motions and conformations in fructose with comparing the glucose. (c) 2007 Elsevier B.V. All rights reserved.