In this work we present a magnetic, structural, and electron spin resonance (ESR) study of the geometrically frustrated MnCr2O4 spinel in an extended range of T (2–1000 K). At the lowest temperature (T<18 K) the ESR lineshape is compatible with the coexistence of spiral and ferrimagnetic spin ordering. Above TC (≈41 K), magnetic susceptibility (χ) and ESR intensity coincide with each other showing the typical behavior of a ferrimagnet. From the χ(T) vs T dependence, absolute values for the three exchange constants JMnCr, JCrCr, and JMnMn were determined. Our results indicate that (i) these values are approximately independent of T, (ii) the antiferromagnetic direct Cr-Cr exchange is the main interaction, and (iii) JMnMn is indeed not negligible as compared with JMnCr and JCrCr. One noticeable anomaly in the temperature dependence of the ESR linewidth is observed at T≈450 K. This behavior is accounted by a 30% variation in the extrapolated high-temperature linewidth and it is attributed to a crystalline distortion not reported previously. Experiments of high-temperature x-ray diffraction allowed us to associate this distortion to a deformation of the oxygen sublattice. ESR and x-ray results are both compatible with a more symmetric high-temperature structure.