Carbonaceous microspheres (CAS) with tunable size, monodispersity and oxygenated functional groups have attracted intensive interest recently owning to potential use in various fields. A facile synthesis of glucose derived CAS is presented by hydrothermal treatment with the help of small amount of anion polyacrylamide (APAM). Different from most other CAS produced with high glucose concentration, the obtained spheres show regular shape and narrow sized distribution, which in turn exert great influence on their application as adsorbent. The results exhibit a substantial reduction in sphere size from 1.57 to 0.48 mu m and 1.77 to 0.75 mu m as the substrate glucose concentration was 0.5 M and 1 M, respectively. A degree of polymerization via intermolecular dehydration and aldol condensation is found reduced by the formation of hydrogen bond via the adsorption of APAM on carbonaceous seeds. The resulted increment in surface charge suppressed the crosslinking reaction thus promoted the monodispersity of CAS, which bestowed the CAS superior performance as an efficient adsorbent for a cationic dye Methyl Blue (MB). Experiments revealed that the CAS, which was further treated with alkaline, can have much higher MB adsorption capacity (348.1 mg/g) than most other reported materials due to the electrostatic interaction with those deprotonated hydrophilic functional groups on CAS surface. (C) 2018 Elsevier B.V. All rights reserved.