The response surface methodology, with a rotatable central composite design, is used in this study for optimizing spray drying process conditions to obtain a fine modified starch powder from “Dominico Hartón” plantains, which are chemically modified with 2‐octenyl‐succinic anhydride. A pilot‐scale spray dryer is used, and the following process factors are evaluated: (A) air inlet temperature (136–154 °C), (B) air outlet temperature (69–81 °C), and (C) rotational atomizer speed (17666–34333 rpm). The response variables are yield, moisture content, and functional properties such as water absorption index (WAI); water solubility index (WSI), swelling power (SP) and degree of substitution (DS). The factors B and C significantly influence the functional properties. The following are the optimal conditions from the process: factor (A), 150 °C; factor (B), 80 °C; and factor (C), 34 858 rpm, with the desirability of 56.7%. Under these optimal conditions, chemically modified plantain starch with desirable quality properties of low moisture content, water activity, and solubility index and high process yield, water absorption index, swelling power, and degree of substitution could be produced.