Abstract: Six new substituted compounds of urea of the general formula -CH=CHNHNR¹R²(R¹=H, R²=C_1-3 alkyl, or R¹=R²=C_1-3 alkyl) have beenprepared by the reactions of a styrylisocyanate with appropriate alkyl-amines. The yields of these compounds are mostly over ninety percent.By the reactions of α-methylbenzyl or p-chloro-α-methylbenzyl isothio-cyanates with different alkylamines, twelve new substituted thioureas havebeen synthesized. Their general formula is X-NR¹R² (R¹ and R² are the same as above; X=Cl, H). The yields of most of the products are over eighty percent.An attempt has been made to synthesize the above substituted thioureas by means of One Step Method, namely, the direct reaction of substituted benzylamine,alkylamine and carbon disulfide. The result shows that whereas dimethylamine can react successfully with the benzyl- or substituted benzylamine and carbon disulfide to give the corresponding substituted thioureas with yields of about seventy percent. Methylamine did not react normally, and the products are mainly sym-dibenzyl or sym-di-substituted benzyl thioureas.Bioassay for these compounds shows that they have herbicidal activi-ties, some of which rank higher than HERBICIDE No. 1 Cl-(CH₃)₂.