Abstract. Terephthalaldehyde-triaminoguanidium chloride covalent organic polymer, Te-TGCl COP can facilely be incorporated with NaNO3 by sonication. Te-TGCl COP incorporated with NaNO3 via ultrasonication adsorbs Methylene Blue (MB) dye. Te-TGCl COP alone shows negligible adsorption capacity for MB, however, when treated with NaNO3, its adsorption capacity emerges slightly. However, Te-TGCl-NaNO3 COP composite resulting from ultrasonication of the NaNO3 treated COP, showed dramatic increase in its adsorption capacity for MB (qe for Te-TGCl COP ≈ 0 mg·g-1; for Te-TGCl-NaNO3= 17.65 mg·g-1). Emergence of MB dye adsorption property in Te-TGCl-NaNO3 COP composite may be attributed primarily to the electrostatic interaction of MB dye molecules with nitrate anions and the sonochemical effect caused fibrous morphological structure of the adsorbent material. The kinetics of MB dye absorption onto Te-TGCl-NaNO3 COP composite exhibits an excellent fit for the pseudo-second order model, suggesting the rate-determining step to be chemisorption. Homogenous monolayer adsorption of MB dye onto Te-TGCl-NaNO3 COP composite can be suggested as the Langmuir isotherm model seemed to be fitted well.