Adsorption was found to be an accepted treatment options to remove geosmin (GSM) and 2-methylisoborneol (2-MIB). It's meaningful to investigate the adsorption capacity of granular activated carbon (GAC) for the two algal odors in water, and the influences of natural organic material (NOM) and particle size. The adsorption process was studied with the four isotherm models (Langmuir, Freundlich, Temkin, and modified Freundlich), four kinetic models (pseudo ﬁrst-order, pseudo second-order, Elovich, and intra-particle), and thermodynamics. The results showed that the adsorption of both compounds could be best described by the modified Freundlich isotherm and pseudo second-order, and the obtained thermodynamic parameters (ΔH0, ΔS0, and ΔG0) revealed that the adsorption was endothermic and spontaneous. Downsizing the particle of GAC was effective for improving the adsorption capacity and rate. The concentrations of the two odorants would be reduced from 500 ng L−1 to less than 10 ng L−1 with the presence of NOM (<20 mg L−1 TOC).