ABSTRACT This experiment was conducted for 42 days, and aimed to investigate the effect of conditioning temperature and time on feed quality, performance, jejunum morphology, ileal microbial population, and apparent metabolizable energy in broilers. According to the completely randomized design (CRD) in a factorial arrangement 2*3 (conditioning temperatures: 65 and 75 °C; conditioning times: 30, 60, and 90 second), 540 one-day-old male Ross 308 broilers were randomly distributed among six treatments with six replications, each replicate including 15 birds. Treatments included: 1) 65-30, 2) 65-60, 3) 65-90, 4) 75-30, 5) 75-60, 6) 75-90. The results showed that 60 seconds of conditioning at 75 °C increased the pellet durability index (PDI) in the starter diets (p<0.05). In the grower and finisher diets, groups (65-60) and (65-90) showed the highest PDI (p<0.05). Broilers fed diets conditioned at 75 °C for 60 s showed more body weight gain (p<0.05). On days 25 and 42, the highest villus height (VH) was observed in treatment (75-60), and 60 s steam conditioning increased crypt depth (CD) (p<0.05). At 75 oC, the number of goblet cells decreased, while their highest number was observed at 30 and 60 s on 25 d (p<0.05). Conditioning at 75 °C for 60 s enhanced the apparent metabolizable energy (AME) in broilers (p<0.05). In conclusion, 60 s conditioning at 75 °C improved the PDI of starter diets, performance, villus height, and AME, while the suitable temperature and pelleting time for grower and finisher diets were (65-60) and (65-90).