The effective area a(e) of three types of highly effective packings such as Raschig Super-Ring, IMTP and Ralu-Flow made from stainless steel and from plastic with nominal size from 20 to 70 mm, are investigated using the Danckwerts method with absorption Of CO2 in NaOH by pseudofirst-order fast chemical reaction. The liquid superficial velocity L varied between 5 and 200 m(3)/(m(2)h). The comparison of the obtained data shows the following: Among all investigated packings at comparable values of the specific area and the liquid superficial velocities, the metal Raschig Super-Rings (RSR) have the highest effective area. They have also the lowest pressure drop versus effective area, at the same gas velocity. At comparable values of the specific area and the liquid superficial velocities the effective areas of the plastic Ralu-Flow and plastic RSR are practically the same, but the first of them have lower pressure drop versus effective area, at the same gas velocity. As it is to be expected, all metal packings have greater effective area than all plastic ones with the same specific area. That means among all investigated 14 packings, the metal RSR have the greatest effective area. (c) 2006 Elsevier B.V. All rights reserved.