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The mesophase pitches produced from petroleum (A240) and coal (HEXT450) have been characterized by several analytical techniques. The kinetics of mesophase formation from these two distinctly different precursor materials have been studied and an empirical kinetic equation proposed. Using the model parameters the petroleum pitch is found to have similar reactivity with respect to mesophase formation when compared with the coal-derived pitch. A new technique of determining mesophase content using computer-assisted image analysis has been demonstrated successfully and reproducibly. The technique is a useful replacement for tedious manual graphing and tracing necessary for area determination. A thermomechanical (TMA) technique for determining the glass transition temperature of pitches has proved to be efficient compared to differential scanning calorimetry (DSC) especially for mesophase pitch. The glass transition of mesophase pitches has been shown to be very prominent and reproducible. A linear correlation between the glass transition temperature and the Mettler softening point temperature of mesophase pitches is also derived using TMA method. A new high-temperature high-pressure (HTHP) viscometer has been developed and tested for high temperature flow studies of the pitch materials. The flow properties of isotropic (A240) and anisotropic (ARA-24) pitch materials have been investigated. The Williams-Landel-Ferry (WLF) equation has been used to describe the viscosity variation with temperature for isotropic pitch (A240) and anisotropic pitch (ARA-24).