Photocatalytic (PC) and photoelectrocatalytic (PEC) degradation of small hazardous biological compounds was accomplished by using uridine as a model compound. The net charge transfer (Q net ) originated from PEC degradation of uridine and blank charge transfer (Q blank ) due to photocatalytic oxidation of water remained constant when the light intensity increased from 20 to 40mW/cm 2 . The effect of solution pH on Q net and Q blank showed that the suitable pH range for this proposed analytical application is between 4 and 9. For both PC and PEC, an increase in the uridine concentration within low concentration range led to a rapid decrease in the mineralization percentage for converting organic nitrogens to both NH 3 /NH 4 + and NO 3 − . With further increase of uridine concentration to 320μM, the PEC mineralization percentages maintained at about 85% and 56% for N oxidized to NH 3 and NO 3 − , respectively. While for PC treatment, the mineralization percentages decreased steadily. Finally, PC and PEC degradation mechanism of uridine was also clarified on the basis of intermediates identified by HPLC/MS/MS and frontier electron densities calculation. Uridine as well as the intermediates can be eventually mineralized into CO 2 , H 2 O and NH 3 or NO 3 − (or both) during PC and PEC degradation with enough reaction time.