Abstract In this research, a newly reported fluorescence molecular probe [N, N’-bis(methylsalicylaldehyde)-4,4’ bipyridinium] dichloride (DALD) was used for selective detection and determination of Fe2+ and Fe3+ in aqueous solutions. The complexation reaction between DALD and Fe2+ and Fe3+ is the basis of the variation in the emission intensity and their quantitative fluorescence determination. The stoichiometries and formation constants of DALD and both ions were obtained by appropriate chemical model and numerical refinement of spectrofluorometric-mole ratio titration data. The selectivity of the probe towards Fe2+ and Fe3+ was tested in the presence of Mn+ (n= 1, 2, 3) cations. None of the other ions show any observable fluorescence signal quenching at the excitation and emission wavelengths (345/456nm). The emission profile of said iron species was in the range of 340-560 nm and has shown a high degree of overlap. The univariate calibration ranges and detection limits of Fe2+ and Fe3+ were 0.7-4.1 μM, 0.7-2.7 μM and 1.3μM, and 0.69 μM, respectively. The orthogonal signal correction-principal component regression (OSC-PCR) as a factor-based and data compression method was used to determine both cations in aqueous solutions simultaneously. OSC-PCR correlates the fluorescence spectra to the concentration of metal ions very well, and the coefficients of determination were 0.9530 and 0.9919 for Fe2+ and Fe3+, respectively. The solution equilibria of interaction between the probe and metal ions were studied and the stability constants of complexes were 10.68 (± 0.05), 1:2 and 4.46 (± 0.12) 1:1 for Fe2+ and Fe3+ respectively. The factors that influenced sensitivity and selectivity were recognized and optimized.