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The most common form of utilization of sesame seed is its roasting, which supplies nutrients to the diet. The objective of this study was to determine the effect of different roasting techniques (using open pan and microwave) on the chemical composition of sesame seed flour and physico-chemical properties of its oil. The raw sesame flour (RSF), open pan roasted sesame flour (ORSF) and microwave roasted sesame flour (MRSF) were analysed for proximate composition, minerals, vitamins, anti-nutritional factors and colour, and the seed oils were analyzed for peroxide and iodine values. The ranges of proximate composition of the flours were: protein 24.3-27.5 g/100g, fat 52.4-59.0 g/100g, crude fiber 3.86- 6.13 g/100g, ash 2.88-3.67 g/100g, carbohydrate 5.4-13.2 g/100g and energy value 552.5 -576.6 kcal/100g. Crude fat, ash, fiber and energy values were significantly higher in MRSF and ORSF compared to RSF. However, protein and carbohydrate values were significantly lower in roasted seeds compared to RSF. Calcium, potassium, phosphorus and magnesium ranged from 439.25-445.02, 342.14-346.77, 427.81-434.77 and 357.38- 364.03 mg/100g respectively with the RSF having the least value. Whereas micro elements such as iron, manganese and zinc ranged from 3.06-6.42, 0.76-1.50 and 2.78-3.62 mg/100g. Thiamine values for RSF, ORSF and MRSF were 40.23, 20.56 and 4.52 mg/Kg respectively; riboflavin values were 21.08, 15.33 and 2.60 mg/Kg respectively while niacin values were and 28.28, 17.30, 2.01 mg/Kg respectively. Roasting in open pan caused significant reduction in phytate and oxalate contents in sesame than roasting in microwave oven. Colour values (L*) of seed flour significantly decreased, whereas a* and b* values increased (P ≤0.05) in ORSF and MRSF compared to RSF. The peroxide values of RSF, ORSF and MRSF were 1.43, 11.21 and 10.02 mEq O2/kg oil respectively while the iodine values were 118.65, 106.44 and 109.71 g I/100g oil for RSF, ORSF and MRSF respectively. The effect of roasting techniques with regard to loss and retention of the nutrients differed significantly (P ≤ 0.05).