The cross-coupling reaction between diethyl ethynylphosphonate (1) and several aromatic iodides under the Sonogashira conditions (Cl2Pd(PPh3)2/CuI/Et3N) gives only minute amounts of the expected 1-alkynylphosphonates. Yields of about 20% are achieved upon using Pd(OAc)2/2PPh3/Et3N in place of the previous catalytic system. Side-reactions involving1and the mine are showntobe responsible for these low yields. Metalation of1with EtMgBr andt-BuLi has been carried out and the M-C≡C-P(O)(OEt)2(M = MgBr, Li) derivatives have been characterizedviareaction with Me3SiCl or Ph3iCl. The easy access to the organolithium compound has made possible the synthesis of the zinc analog (M = ZnCl) which reacts with aromatic iodides (C6H5I,p-MeOC6H41,p-O2NC6H4I,p-1C6H4I, 2-iodothiophene), in the presence of Pd(PPh3)4, to give diethyl 1-alkynylphosphonates in reasonable yields. Oxidative dimerization of1under the Hay conditions (CuCl/TMEDA:acetone/air) gives the symmetrical diacetylenic diphosphonate (EtO)2(O)P-C≡C-C≡C-P(O)(OEt)2in high yield.