Treatment of N,N'-dimethyl urea with ClPPh(2) and NEt(3) as auxiliary base in thf affords the title compound PPh(2)NMeC(O)NMeH (1) in high yield. The monophosphino urea derivative 1 constitutes the first isolated and fully characterized representative of this class with a NH functional group. Evidence for a solvent effect in the synthesis of 1 is given and the X-ray crystal structure determined. The reaction of 1 with [Mo(CO)(4)(NCMe)(2)] and the hemilabile character of the ligand 1 in the obtained P,O-chelate complex cis-[Mo(CO)(4)(eta(2)-PPh(2)NMeC(O)NMeH)] (2) are described. Furthermore, synthesis of the known bisphosphino urea derivative CO(NMePPh(2))(2) (3) starting from 1 is reported.