The Center of Molecular Immunology has developed CIMAvax therapeutic vaccine against lung cancer, one of those showing the highest incidence in mortality worldwide. The vaccine works by inducing an antibody response against epidermal growth factor (EFG), thus reducing the interaction between EGF and its receptor (rhEGF-EGFR). As a result, the vaccine inhibits the growth of the cancer cells. This vaccine is based on the conjugation of rhEGF and carrier protein rP64K derived from Neisseria Meningitidis. Chemical conjugation between the two proteins is carried out by using the glutaraldehyde as a homobifuncional linker. Under these conditions the product is obtained with some degree of heterogeneity, which affects the vaccine expansion to the international market due to regulatory issues. Our work has the objective to optimize the process of conjugation of rhEGF and protein rP64k. The influence of concentration and the use of a reducer agent in the chemical reaction were assessed. The conjugates were characterized by high resolution liquid chromatography using a column of molecular exclusion, SDS-PAGE and Western Blot. Immunogenic essays claim that optimized conjugates show antibody titers in the same order of the conjugates from the current vaccine. The results represent a technological advance with respect to the present method of obtaining the conjugate rhEGF-rP64K.