A synthesis of dendrimers and hyperbranched polymers by using cycloaddition of cyanoguanidine to nitriles and cyanoethylation reaction is reported. Both reactions proceeded in the presence of a basic catalyst (alkaline hydroxides and Triton B, respectively). The guanamine dendrimerization process has been carried out up to 4th generations ended with cyano or amine groups. Intermediates and product substances, as well as by-products were identified by FT-IR, 1H and 13C NMR, MS, FIB-MS, and elemental analysis. Hyperbranched polymers were characterized by gel permeation choursomatography (GPC). Polyguanamine dendrimer (PGD) molecules exhibited expanded form in dimethylacetamide solution and low polydispersity (1.12–1.26). Observed contraction of the macromolecules was growing towards higher generations reaching an extreme at generation 4. The degree of branching of the products were within the range of 0.81–0.87 on the 0–1 scale. Decyanoethylation, hydrolysis, and intramolecular cyclization, as side reactions, were observed on the cycloaddition steps of dendrimerization. Some main stream dendrimerization products, i.e., tetrakis [2-(2,4-diamino-1,3,5-triazin-4-yl)ethyl]2,4-diamino-6-phenyl-1,3,5-triazine and 2,2,6,6-tetrakis[2-(2,4-diamino-1,3,5-triazin-6-yl)ethyl]cyclohexanone as well as by-products, i.e., 2,6,6-tris[2-(2,4-diamino-1,3,5-triazin-6-yl)ethyl] cyclohexanone, 2,6,6-tris(2-cyanoethyl)cyclohexanone and a dilactam have been isolated as new compounds. Spectral data for N2N2N4N4-tetrakis(2-cyanoethyl)-6-phenyl-1,3,5-triazine, 2,2,-6,6-tetrakis(2-cyanoethyl)cyclohexanone, 1,1,1-tris(2-cyano-ethyl)propanone-2 and 1,1,1-tris[2-(2,4-diamino-1,3,5-triazin-6-yl)ethyl]propanone-2 have been complemented.