<p>Metal nanoparticle based electrodes are powerful platforms to develop advanced electroanalytical systems. However, successful responses require the efficient attachment and stabilization of these nanostructures to the electrode. In this work, a sol-gel mesoporous carbon ceramic composite was modified with silver nanoparticles (AgNPs) stabilized by the ionic silsesquioxane containing the 1,4-diazoniabicyclo[2.2.2]octane nitrate group and designed to present both stable AgNPs and porous structure. The electrode, developed with this conductive carbon ceramic composite, presented smaller than 10 nm and non-coalescent AgNPs, resulting in improved electrochemical response for sulfamethoxazole (SMX) and trimethoprim (TMP). The detection of these antibiotics in potable water, foods and biologic fluids is essential because they can produce many undesirable effects in the human body. Differential pulse voltammetry studies using the developed electrode, resulted in sensitive responses, which led to low detection limits of 60 nmol L⁻¹ and 120 nmol L⁻¹ for SMX and TMP, respectively. Also, the electrode was able to detect both analytes simultaneously. This study sheds light on the strategy of increasing the load of metal nanoparticles into electrodes, while guaranteeing their stability during electrochemical tests by using the silsesquioxane as stabilizer and attaching agent.</p> Graphical Abstract <p></p>