Abstract: A rhodamine-based probe bearing an N,N-dimethylaniline unit was developed as a fluorescent chemodosimeter for Ce4+ in aqueous media. Importantly, the sensor can selectively respond to Ce4+ over other commonly coexistent metal ions (such as La3+, Ce3+, Pr3+, Nd3+, Sm3+, Eu3+, Gd3+, Er3+, Tb3+, Ho3+, Tm3+, Yb3+, Lu3+, Y3+) in aqueous media with a rapid response time. The system, which utilizes an irreversible Ce4+-promoted oxidation reaction, responds instantaneously at room temperature with linear proportionality to the amount of Ce4+. [Copyright &y& Elsevier]