2-Cyano-3,12-dioxoolean-1, 9-dien-28-oic acid (CDDO) is a semisynthetic triterpenoid. CDDO derivatives with an amide, butyl ester (BE), imidazolide (IM), or trifluoroethyl amide (TFEA) group at position C-28 of CDDO were evaluated in glial and neuronal cells, in vitro. Changes in intracellular NADPH:quinone oxidoreductase (NQO1) levels, protection against oxidative toxicity, endotoxin-induced free-radical production, and the median lethal concentration (LC50) were assessed. All four CDDO derivatives at nanomolar concentrations increased NQO1 levels in astrocytes and moderately in neurons, but not in microglial cells. Pretreatment with 100 nM of CDDO-amide, CDDO-TFEA, or CDDO-IM protected astrocytes from hydrogen peroxide toxicity. Only CDDO-amide protected neuronal cells. Pretreatment of microglial cells with CDDO derivatives at nanomolar concentrations attenuated endotoxin-induced nitric oxide protection. The effectiveness for NQO1 induction, protection against oxidative toxicity, and attenuation of nitric oxide production, as well as cell viability at higher concentrations, varied among the derivatives with different functional groups at C-28. CDDO-amide had comparable or even a greater effectiveness at altering cytoprotective and immunomodulatory properties while having higher LC50 values for each neural cell type examined. These results indicate that derivatives of CDDO modulate important pathways relevant to many neurological diseases that involve both chronic inflammation and free-radical damage with variable effects based on the functional group at C-28 and cell type.