A bio-active phytochemical, curcumin, was isolated from dried rhizomes of Curcuma longa using Soxhlet, microwave, ultra-sonic and supercritical carbon dioxide assisted extraction techniques. The quantification of curcumin in resultant extracts was performed using pre-validated HPLC methodology. The critical parameters viz, effect of pre-irradiation and soaking solvent on the curcumin yield were studied. The extraction efficiency of all the above described techniques was established in terms of percent curcumin yields and extraction rate constants. Prior to extraction, microwave and ultra-sonic irradiation of dry curcuma powder resulted in 68.57 and 40.00% curcumin yield, respectively, whereas water soaked irradiated curcuma powder yielded 90.47 and 71.42% curcumin recovery respectively, during a total extraction period of five minutes. The maximum extraction rate constant of 47.49 x 10(-2) min(-1) was observed when using microwave assisted acetone extract of water soaked curcuma rhizomes. The comparison of Soxhlet, microwave, ultra-sonic and supercritical carbon dioxide assisted extraction in terms of percent yield and required extraction period showed that microwave assisted extraction technique was more efficient for the curcumin extraction from powdered C. longa rhizomes. (C) 2011 Elsevier B.V. All rights reserved.