A systematic investigation of effect of various parameters, for example, temperature, speed of agitation, particle size, and solid loading, on the percentage extraction of catechin hydrate (CH) and epicatechin (EP) was conducted The extraction was performed with water, methanol, and ethanol Water was found to be the best solvent for both Percentage extraction of CH was found to decrease with temperature beyond 46 degrees C, however, this is not the case for epicatechin The thermal stability analysis of both the compounds was performed to ensure decomposition This supported the experimental observation of batch extraction Size of particle has little effect on percentage extraction of EP, but it increases for CH with decrease in particle size, which is probably because of decrease in diffusion path length Assuming flat geometry of the particles, the process is modelled and compared with experimental data at different experimental conditions The experimental data fitted well with the model proposed by Wongkittipong The effective diffusion coefficients through the solid matrix of Indian green tea leaves for CH and EP estimated from the diffusion model were found to be in the range 1 29 x 10(-13) to 3 40 x 10(-13) m(2)/s and 1 20 x 10(-13) m(2)/s to 3 38 x 10(-13) m(2)/s, respectively The effect of temperature on diffusion coefficient of CH and EP was determined using the model The energy of activation required for diffusion was found to be 32 78 and 30 28 kJ/kmol, respectively for CH and EP