Using standard thermodynamic data it is shown that tho oxidation of glucose by nitrogen to give carben dioxide and ammonia is all ovel'a.ll maction that involves a substantial evolution of heat and deel'easfl in ii'ee elH'rgy. 'I'his is not in a(lCOrdallce with literature statements that, biological nitrogen fixation is onrlothormie. In tho concluding section a Frost diagram is used to sun'oy the thcrrnodynamie data of oxidation l'C'adions related to nitrogen fixation.