A new Trö ger's base-containing aromatic dihydrazide, 2,8-bis(carboxylic)-6H, 12H-5,11-methanodibenzo-[b,f] [1,5]-diazocine dihydrazide, was prepared by the condensation of ethyl p-aminobenzoate with hexamethylenetetramine in the presence of trifluoroacetic acid, followed by converting to the dihydrazide with a high yield and high purity. A series of novel aromatic polyhydrazides were prepared from the Trö ger's unit containing dihydrazide and various aromatic diacyl chlorides via low-temperature solution polycondensation in quantitative yields. All the polyhydrazides were amorphous and readily soluble at room temperature in polar organic solvents such as N,N-dimethylacetamide and N-methyl-2-pyrrolidone. These polymers could be solution cast into transparent, tough, and flexible films with good mechanical properties. They had useful levels of thermal stability associated with good glass transition temperatures (163-172 C), 10% weight-loss temperatures in excess of 460 C, and char yields at 800 C in nitrogen higher than 39%.