Graphical Abstract: Adsorption of strontium ions from aqueous solutions on active carbons CAN-7 and oxidized CAN-8 has been studied. Obtained results showed that the adsorption isotherms for strontium ions from aqueous solutions are well described by the Langmuir and Dubinin-Radushkevich equations, respectively. The surface heterogeneity of activated carbons CAN-7 and oxidized CAN-8 has been assessed by using Freundlich equation.