The present studywas designed to synthesize lanthanum doped feathers-type ZnO nano-flower (feathers-type La3+-ZnO nano-flower), that are specified via Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). To simultaneously determine codeine and diclofenac using feather-type La3+-ZnO nano-flower modified carbon paste electrode (La3+-ZnO/CPE), an original cost-efficient and simple methodology is presented. Evidently, La3+-ZnO/CPE proved to be a prospective, stable, sensitive and chemically reliable electrochemical sensor to determine diclofenac and codeine simultaneously with no intervention or overlapping of voltammetric peaks or signals. Codeine electro-analytical sensing was examined via La3+-ZnO/CPE across an extensive concentration range at a relatively low detection limit of 0.01 mu M, (3S/N). La3+-ZnO/CPE of nanoscale feathers-type La3+-ZnO structure displays favorable practicality in analytical terms to accurately and simultaneously determine diclofenac and codeine within real specimens with exceptional recoveries. The outcomes prove exceptional La3+-ZnO/CPE performance in regard to facile, reliability and sensing capabilities which may favorably decrease the relevant processing expenses for routine analysis and scalable production. (c) 2019 The Electrochemical Society.