Studies were carried out on dry ash of red mangrove (Rhizophora mangle L) bark, an agricultural waste, to determine the potassium ion concentration in it, by titratory and spectrophotometric methods. 100gm of the dry ash were dissolved in 500cm3 of buffer solutions (pH 1-7) and the aqueous extract from the bark subjected to titration against standard HCl and CH3COOH in the concentration ranges of 0.5-2.0 M,while AAS was carried out using 5 gm of the dry ash in GBC Avanta flame atomic absorption spectrophotometer version 2.02 . The results obtained from the titration reaction revealed that there were generally low levels of potassium ion concentration (14.820 gm/dm3 and14.333 gm) in all the buffer solutions with both titrants (HCl and CH3COOH). This result was in agreement with the results of AAS result (18,255.00 ppm). The percentage purity calculated revealed that the potassium ion obtained from the red mangrove bark aqueous extract (RMBAE) had a purity of 69.94%,showing high purity of the potassium obtained by these methods. The proposed methods were successfully employed to determine potassium ion concentration in red mangrove bark aqueous extract (RMBAE) in buffer media. One way analysis of variance revealed significant differences in the nature of acid as a function of the amount of potassium ion produced. The result also revealed that the mineral acid (HCl) gave better potassium ion concentration than the weak or organic acid (CH3COOH)..
