A tar-base concentrate from a hydrocracked shale oil naphtha was separated by gas-liquid partition chromatography using nonpolar and polar columns. Final cuts were analyzed by mass, infrared, and nuclear magnetic resonance spectrometry. Fifty individual compounds were identified and eight additional structures are proposed as possible components of the concentrate. Alkylpyridines comprised about 64 percent of the bases and alkylanilines about 33 percent; the rest of the bases were quinoline and small quantities of cycloalkanopyridines. Substitution patterns for both the alkylpyridines and alkylanilines showed that a substitution was favored over b or y, and y was favored over b.