•Roasting temperature can affect the quality attributes of chia seed and oil.•Higher roasting temperatures decrease the nutritional contents of chia seed and oil.•Both the individual phenolics and fatty acids in chia seed are heat sensitive.•Lower chia seed roasting temperature can result in better retention of nutrients. The effect of roasting of chia seed at different temperatures (90, 120, 150 and 180 °C) on bioactive constituents in extracts and on the quality of oil was evaluated. At higher temperatures, crude protein and ash contents increased, whereas total phenolic, flavonoid, carotenoid, and antioxidant activities decreased. The predominant phenolic constituents were myrcetin, and rosmarinic, 3, 4-dihydroxybenzoic, caffeic, and gallic acids, which all decreased with increasing temperatures. Notably, myrcetin content ranged from 75.59 mg/100 g (at 100 °C) to 85.49 mg/100 g (for control). Tocopherols (ɣ and α type) were predominant nutrients and their levels ranged from 654.86 mg/100 g (at 180 °C) to 698.32 mg/100 g (for control). Concentrations of linolenic (59.84%), linoleic (20.57%), and oleic (10.09%) acids from unroasted chia seeds were higher than those from roasted ones. This study revealed that chia seeds should be heated at temperatures below or equal to 90 °C in order to preserve their nutrient profile.