Five pairs of diastereoisomeric dioxetanes, cis- and trans- 2a– 2e, were synthesized. These dioxetanes underwent intramolecular charge-transfer-induced decomposition with accompanying emission of orange light in TBAF in DMSO ( system A ) as a complete homogeneous system and in [K⊂(18C6)] + t-BuO − in PhH–THF ( system B ) as a sterically anisotropic environment. Maximum wavelength ( λ max CTICL) of chemiluminescence did not vary practically with the triggering system. The λ max CTICL was little affected also by substituents on the upper-Nap of dioxetanes 2, nor by the difference in their stereochemistry, namely, cis- or trans-isomer. On the other hand, chemiluminescent efficiency was found to split up depending on stereochemistry of 2. Dioxetane 2b bearing a methoxycarbonyl group on the upper-Nap gave significantly weak light, while its free carboxylic acid analog 2c afforded light effectively.