The present work reports room temperature IR and Raman study of R-NH-CH2-CO-NH-CO-NH2 alkylaminoacetylureas (R=C3H7, C4H9, C5H11, C6H13, C7H15, C8H17, C9H19, C10H21, C12H25, C14H29, C16H33 and C18H37). The experimental energy levels have been compared to those obtained from DFT chemical quantum calculations performed with the use of B3LYP/6-31G (d,p) basis for the R=C3H7 derivative. Energies of 66 vibrational states have been calculated for this molecule. Its molecular symmetry was taken as C1 and was optimized in the both quantum models applied. The role of the hydrogen bond in the stabilization of the structure has been analyzed.