Our objective was to determine whether initiation of febuxostat during an acute gout flare prolongs the current episode. In this randomized, placebo-controlled, single-blinded, multicentre trial, patients with acute gout flares within 72 h were randomized (1:1) to the placebo and febuxostat (40 mg/day) groups. All patients were administered Diclofenac (150 mg/day) for 7 days and then open-labelled on the 8th day. Febuxostat 40 mg daily and Diclofenac 75 mg daily were administered from day 8 through 28 for the remission period. The dose of diclofenac was 150 mg/day before remission in both arms, and the original protocol was maintained until remission. The primary outcome was "days to resolution". We randomized 140 patients, 70 into each arm. The mean days to resolution was 5.98 days (median 7.00, IQR 2.45 days) for the placebo and 6.50 days (median 7.00, IQR 3.67 days) for the febuxostat group (p= 0.578). The rate of resolution within 7 days was 84.38% for the placebo group and 76.92% for the febuxostat group (p= 0.284).There were no statistically significant differences in joint pain, swelling, tenderness, and erythema scores at days 1, 3, 5, and 7. The mean serum uric acid levels were 507.54 and 362.62 μmol/l for the placebo and febuxostat group respectively on day 7 (p= 0.000). The rate of recurrent gout flares was 10.00% for the placebo group and 6.56% for the febuxostat group from day 8 through 28 (p= 0.492). Initiation of febuxostat administration during an acute gout flare did not prolong the duration of acute flares. Chinese Clinical Trial Registry, http://www.chictr.org.cn/, ChiCTR1800015962. © The Author(s) 2021. Published by Oxford University Press on behalf of the British Society for Rheumatology.