This interdisciplinary project aims to develop and employ a highly sensitive, broadband, highfrequency electron spin resonance spectrometer based on torque magnetometric detection. Starting from our recent preliminary work, we will first extend the applicability of torque-detected ESR, and optimize the spectrometer as well as the measurement protocol. The implementation of zero-deflection measurement capabilities will increase the dynamic range, while soft cantilevers and alternative detection schemes improve the sensitivity. This will enable us to carry out highly sensitive frequency-, field-, and angle-dependent measurements at high-frequencies on “real life” samples with limited numbers of spins. These samples include surface arrays of spin centers, and high-spin, high-anisotropy centers in the active sites of metalloproteins.