The synthesis of cis-1,3-diformylcyclohexane by a hydride reduction of the dimethyl ester of cyclohexane-cis-1,3-dicarboxylic acid is described. An inversion of configuration occurred during an attempt to prepare trans-l,3-diformylcyclohexane by a similar route, cis-1,3-Divinylcyclohexane was prepared by a Wittig reaction on the corresponding dialdehyde. Polymerization of cis-1,3-diformylcyclohexane using a cationic catalyst gave high yields of thermally unstable polymers. Soluble fractions of the polymers contained some residual aldehyde groups. Spectroscopic data confirmed that these polymers contained 3-oxabicyclo[3,3,1] nonane rings formed through a cyclopolymerization mechanism. Polymerization of cis-1,3-divinylcyclohexane using a Ziegler catalyst resulted in soluble polymers containing little residual unsaturation. This soluble polymer, from the evidence, is a cyclopolymer containing bicyclo[3,3,1] nonane units.