We report on the design and characterization of a single chip integrated pulsed electron spin resonance detector operating at 9.1 GHz. The microsystem consists of an excitation microcoil, a detection microcoil, a low noise microwave preamplifier, a mixer, and an intermediate frequency (IF) amplifier. The chip area is about 0.7 mm2. To exemplify its possible applications, we report the results of single pulse, Rabi nutation, Hahn echo, two echoes, Carr-Purcell, and inversion recovery echo experiments performed on 0.02 and 0.05 nL samples of α, γ-bisdiphenylene-β-phenylallyl (BDPA) and 1% BDPA in polystyrene (BDPA:PS) at room temperature. The measured spin sensitivity is about 8 × 107 spins/Hz1/2 on a sensitive volume of about 0.1 nL. The microsystem power consumption is less than 100 mW, the radio frequency (RF) input bandwidth is 8.8 to 9.8 GHz, the IF output bandwidth is DC to 350 MHz, and the deadtime is less than 30 ns.