Encapsulation of both 3,4-ethylenedioxythiophene (EDOT) and terthiophene (TTh) into a cyclodextrin-based metal- organic framework (CD-MOF) was successfully achieved upon use of an adsorption technique. The average amount of EDOT introduced into the CD-MOF was calculated to be 4.3 molecules per hydrophilic nanopore. On the other hand, from the relationship between the molecular size of TTh and the nanopore volume, TTh was evaluated and found to be mostly isolated in each hydrophobic nanopore of the CD-MOF. Co-oligomerization of EDOT and TTh in a CD-MOF was initiated by exposure to I z vapor and subsequent heating at 80 degrees C for 6 h. A trace amount of the co-oligomers consisting of two TTh molecules and four or five EDOT molecules was detected by using matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS). The chemical structure of the co-oligomer was considered to be TTh bound at both ends of the EDOT tetramer or pentamer.