Abstract The objectives of this research are to extract the air-dried stem bark (500g) of citrus aurantifolia with methanol using cold infusion (maceration) technique, partition the extract with solvents of graded polarities (n-hexane, ethyl acetate, n-butanol suspended in water) and phytochemically screened and fractionate and purify the n-butanol partitioned portion using a combination of column and thin layer chromatography and finally subject the possible pure fraction(s) to gas chromatography and mass spectrometry (GC-MS) analysis. The methanol crude extract yield 14.90% w/w dark green in colour, gummy in texture. The n-hexane partitioned portion yield 0.44% w/w light green in colour oily paste texture, ethylacetate partitioned portion yield 5.32% w/w dark brown in colour, gummy in texture, while n-butanol yield 21.04%w/w, brown in colour, gummy in texture and finally aqueous partitioned portion yield 52.08% w/w brown in colour power in texture respectively. The presence of metabolites such as carbohydrates, cardiac-glycosides, terpeniods, flavonoids, tannins and phlobatannins were recorded in the methanol crude extract while, anthraquinones, alkaloids and saponins were not detected in methanol crude stem bark extract. Whereas cardiac-glycosides, terpeniods and flavonoids were present in n-hexane portion and n-butanol portion but carbohydrates, anthraquinones, tannins, saponins, phlobatannins and alkaloids were not found in both of the portions. The purification of compounds was done by using a combination of column and thin layer chromatography techniques. The n-butanol partitioned portion was subjected column chromatography after, rerunning, recombination and pooling four compounds, coded Ca1, Ca2, Ca3 and Ca4 were obtained. The melting points were sharp and uncorrected. In gas chromatography and mass spectrometry (GC-MS) analysis of compound of sample Ca1 fourteen compounds were identified by comparison with the library of NIST. Among the compounds, were found to be 3, 5, 9-Trioza-5-Phosphaheptacos-18-en-1-aminium, Pentacosanoic acid, Oleic acid, 7, 8-Epoxylanostan-11-ol. Analysis of Compound of sample Ca2 shows that only one compound was identified by comparison with the library of NIST. The compound was found to be 3H-Cycloocta[c]pyran-3-one. Analysis of Compound of sample Ca3 shows eight compounds were identified by comparison with the library of NIST. Among the compounds were found to be 1, 3-Dioxane, Pregn-5-en-20-one, 9-Octadecenoic acid, Heptadecanoic acid, Epoxylanostan-11-ol. Analysis of Compound of sample Ca4 shows that eight compounds were identified by comparison with the library of NIST. Among the compounds were found to be Glycidol stearate, Andrast-4-ene-3-one, Octadecanoic acid, Dihydromorphine. The dihydromorphine which believed to be a reduced formed of morphine with a molecular formula of C17H21NO3. It has been reported that the 7, 8-double bond of morphine also is not required for analgesic activity as indicated by the relative analgesic potency of dihydromorphine. Also, oxidation of the 6-OH of dihydromorphine to yield hydromorphone further increases activity.