This study aimed to optimize the synthesis of a cosmetic ester (decyl oleate) catalyzed by immobilized lipase from Thermomyces lanuginosus (TLL) on amino-functionalized rice husk silica (Amino-SiO2), i.e. a homemade biocatalyst prepared via ionic adsorption. Functionalized support has been characterized by ATR-FTIR, TGA-DTA, and TEM analyses. The effect of important parameters on ester synthesis has been evaluated through a full factorial design in Central Composite Rotatable Design (CCRD) mode. Under optimal experimental conditions, maximum ester conversion percentage of 87% was observed after 105 and 180 min of reaction time in iso-octane and solvent-free systems, respectively. However, similar reaction rates of around 10 mM/min were obtained for both reaction systems. Ester synthesis in a solvent-free system is a kinetically controlled process, which has been confirmed by calculating its Damkohler number (Da = 7.63 x 10(-5)). Reusability tests showed that the biocatalyst retained all of its original activity after eight successive reaction cycles in a solvent-free system. These results show that this homemade biocatalyst can be successfully used in cosmetic ester synthesis through a clean technology process due to its high catalytic activity and reusability. (C) 2018 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.