The effect of pH on retention of Mn-56 produced by the (n, gamma) process in lanthanum and strontium permanganates has been investigated. It has been observed that the retention is apparently pH-independent over the pH range from 2.5 to 9.0; however, a pronounced effect was seen in low (pH 1.0-2.0)- and high (pH 9.5-12.5)-pH regions for both solid and solution phase irradiated samples. The results obtained are discussed in the light of existing ideas, which would be of help for a better understanding of the chemical stabilization of the recoil 56Mn atom and its subsequent participation, with reactive intermediates thus helping in the mechanism of recoil chemical stabilization of 56Mn in lanthanum and strontium permanganates. (c) 2006 Elsevier Inc. All rights reserved.