Chemistry Research Lab, Deshbandhu College, University of Delhi, New Delhi-110 019, India E-mail : mansingh50@hotmail.com Manuscript received 6 June 2005 Both surface tension (��) and viscosity (��) for 0.0050 to 0.2560 kg mol-1 urea, methylurea and dimethylurea solutions have been measured with Survismeter for Friccohesity (��/Sm-1), derived from frictional and cohesive forces. The limiting (��0) and slope values S�� of �� at infinite dilution, m = 0, are determined from �� vs m mol kg-1 fit for intermolecular forces coefficient (��0imf) and influence of temperature, K. The S�� values project an effect of concentrations on pairwise interactions of ureas. And decrease in ��0imf and S�� values from urea to dimethylurrea focus contribution of -CH3 group to hydrophobic interactions over the hydrophilic, due to -NH2 and >CO- groups of urea. Substitution of H by -CH3 is noted to weaken hydrogen bonding strength of >CO-.