The present invention relates to a process for isolating temozolomide from an acidic solution containing temozolomide comprising subjecting the acidic solution of temozolomide to a counter-current continuous liquid-liquid extraction using water immiscible solvent. The present invention also relates to a process for purifying temozolomide comprising refluxing temozolomide in an acetone-water mixture having a pH from 2.5 to 4.5 followed by recovering purified temozolomide.