To improve the disadvantage of the low reactivity and reduce the high curing temperature of epoxy resin cured by dicyandiamide (DICY), DICY is chemically modified with phenyl hydrazine and a new curing agent, LB-A, is developed in this research. The structure, the curing behavior, and reaction kinetics of LB-A curing epoxy resin are investigated. Results show that the DICY is modified successfully and the well-defined structure of DICY is destroyed after modification. Consequently, a new curing agent in a noncrystal form is resulted. Thereupon, the reactivity and compatibility between the epoxy resin and the curing agent are improved appreciably using LB-A instead of DICY. Meanwhile, the curing temperature and activation energy of the curing reaction decrease outstanding, whereas the rate constant increases remarkably. In addition, the compressive strength and the adhesive strength in shear by tension loading of the resulting epoxy resins have been increased using LB-A instead of DICY as the curing agent. (c) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 127: 1895-1900, 2013