The polymerizations of acetylene by coordination catalysts composed of neodymium com-pounds(Nd(P204)3
Nd(P507)3
Nd(NO3)3 . 3P350
Nd(BA)3 . 3H2O
Nd(acac)3 .3H2O)
trialkyl aluminum and a third component have been investigated. It is found that neodymium phosphonata-trialkyl aluminum-2-ethyl hexyl phosphonate system shows higher catalytic activity and gives high cis% polyacetylene films at 30℃.