Microcystins (cyclic heptapeptides), produced by a number of freshwater cyanobacteria, are of health concern in potable water supplies. In this article, the adsorptive removal of microcystin-RR (MCRR) from the aqueous solution by a low-cost adsorbent, peat, was investigated. The BET surface area of peat was found to be 12.134 m2/g. The adsorption process was pH dependent, with maximum adsorption occurring at pH 3. Kinetic studies revealed that the adsorption of MCRR onto peat was a rapid process. The adsorption capacity (Qmax) as revealed by the Langmuir model was found to be 286 μg/g at pH 3. Among various desorption media studied, strong alkali solutions (2 N NaOH) showed the highest desorption (97%). Thus, peat has potential to be used as an adsorbent for the removal of the cyanotoxin, MCRR, from drinking water.