Hydroxyethyl cellulose (HEC)/NaOH frozen rods were applied in the investigation of the coagulation kinetics. The influence of coagulation variables such as types of coagulants, coagulation temperature, concentration of coagulant, and content of HEC on coagulation rate was intensively studied based on boundary movement theory. It was confirmed that the coagulation of HEC was actually diffusion-controlled process and sometimes accompanied with chemical reactions. The coagulation rate of HEC rods in strong acid (sulfuric acid) exceeded that in weak acid (acetic acid), while the coagulation rate in ethanol was the slowest. It was hard to determine the coagulation rate of HEC frozen rods in deionized water without pre-solidifying because of the difficulty in keeping the cylindrical shape of sample due to the low strength of the coagulated surface layer. Besides, the increase of acid concentration, temperature, or content of HEC would contribute to the improvement of coagulation rate. This study is important for understanding and controlling the shaping process of HEC.