A previous study showed that the use of a capsicum oleoresin based additive (Luctarom Convert – LOM, Lucta S.A.) was able to improve dietary fat digestibility in broilers. The present study aimed to evaluate the effect of LOM on growth performance of broiler chickens under summer conditions in Spain, where animals are fed with highly concentrated energy diets. A total of 720 1 d-old male Ross 308 broilers were used until 32 d of age. A mash commercial diet based on cereal-soya and soybean oil was used comprising two feeding phases: starter (1-21 d, 2980 Kcal/kg, 1.31% dLys, 0.6% dMet, and 4.9% EE) and grower (22-32 d, 3150 Kcal/kg, 0.99% dLys, 0.48% dMet, and 6.6% EE). Animals were randomly distributed into 12 pens (60 birds/pen), and allotted to 2 experimental treatments (6 pens/treatment): control (CON, without additive) and LOM (250 ppm and 125 ppm, in starter and grower diets, respectively). Each treatment had 6 replicates of 60 birds/pen. Body weight (BW), average daily gain (ADG), feed intake (FI) and feed conversion ratio (FCR) were recorded at 7, 14, 21 and 32 d of age. Data were analyzed using a mixed-effects model with repeated measures (SAS software). A significant interaction between treatment and time was observed for ADG (P < 0.001). ADG was improved in LOM compared CON (+4.79%) during the grower period (121.7 vs 127.5 g/d, CON and LOM, respectively); this gain in ADG was accompanied with a numerical improvement (P=0.18) in FCR (1.38 vs 1.36, CON and LOM, respectively). In conclusion, the use of LOM showed positive effects in growth performance during the grower phase, when animals received high energy diets.