A novel colorimetric sensor has been proposed for sensitive and accurate detection of iodine forms using polymethacrylate matrix, which also has the outlook for use with samples without pre-treatment and is suitable to fit in a portable instrument for in situ iodine analysis. This determination method is based on interaction of polymethacrylate matrix with iodine forms followed by measurement of absorbance at 370 nm. The principle of this colorimetric sensor is not ordinary colorimetry, but a new colorimetric strategy that combines solid phase extraction and spectrophotometric determination of a target substance following completion of the color change processes. This method ensures determination of 0.05-80.0 µg·g-1 of iodine with the detection limit of 0.02 µg·g-1. The testing results show that this polymethacrylate matrix can be used for determination of iodine in solutions, food grade salt and iodinated mineral water.