A chemical reaction type chemodosimeter immobilized on mesoporous silica materials (CFMS) was reported and showed fluorescent ratiometric, colorimetric, and even naked-eye recognizable manner with a detection limit of similar to 2 mu M for mercury (II). The characterization of CFMS indicated that the ordered mesoporous structure was well preserved after the immobilization. It was found that only the addition of Hg2+ resulted in significant color change and large fluorescence spectral shift whereas other cations didn't induce any color or emission change. In addition, CFMS was also coated as films onto glass substrates. When aqueous Hg2+ rapidly passed through the glass substrate, the green emission of supported CFMS became blue under a 365 nm lamp. These considerable signal changes, easy-to-prepare materials, and simple-to-operate technique suggested the potential application of CFMS for fluorescent ratiometric detection of Hg2+ ion in the practical environmental field. (C) 2010 American Institute of Chemical Engineers AIChE J, 56: 2957-2964, 2010