The increased demands of healthy natural foods represent a challenge for food processors. This work aimed to study the effect of fat substituting with chia (Salvia hispanica L.) gel in producing low-fat cake. Fat was substituted with chia gel containing chia seed with the levels of 25, 50, 75 and 100% which named CG-25, CG-50, CG-75 and CG-100 respectively. The results reveal that chia seeds are a good source of nutrients since it contains 24.95 g/100 g protein, 36.27 g/100 g lipid and ash 5.11 g/100 g (on dry basis) as well as had high caloric value (563.91 kcal/100 g). Regarding the physiochemical properties, cake volume was decreased as substitution level increased (above 50%). Similarly, the cake's specific volume was decreased by increasing of fat substitution level with chia gel. Cake hardness was increased as the substitution level increased, since cake sample CG-25 was more firm than control sample but was less firm than cake sample CG-100. The crust and crumb color of cake samples containing chia gel became darker than that of control sample. The highest (P < 0.05) contents of moisture and protein were recorded for cake sample which formulated with fully substitution of shortening with chia gel (38.90 and 15.75%, respectively) while the lowest contents of the same parameters were observed in control sample (36.48 and 12.01%, respectively). As well as contents of carbohydrates, ash and fibers were increased (from 29.82 to 38.96; 2.06 to 2.41 and 1.58 to 1.72 g/100 g., respectively) as the substitution level of fat increased. On contrary, lipids content was significantly (P < 0.05) decreased as the level of substitution increased, so cake sample CG-100 exhibited a great reduction ratio (79.7%) in lipid content in relation to control sample. Also, the results indicated that the highest caloric value was recorded for control sample (343.99 kcal. /100g), while the cake sample CG-100 exhibited the lowest caloric value (254.66 kcal. /100g). Fatty acids profile was changed by substitution of shortening with chia gel, the decrement ratios of saturated and monounsaturated fatty acids for cake sample CG-100 were 84.17 and 82.46%., respectively, whereas the increment ratio of polyunsaturated fatty acids was 44.62%. Also, sensorial results indicated that no significant effects were observed between different cake samples and control sample in most qualities and they generally were acceptable. Finally, low fat cake can be produced by fat substitution by chia gel with keeping good physiochemical properties and nutritional quality, as well as consumer acceptability.