Recent results are summarized of gamma-radiolysis of dilute nitrate solutions at neutral (p)H in the presence of oxygen and hydrogen as radical scavengers. Complete analysis of the system leads to values of the primary yields showing a net deficit of oxidized products of approximately 0.4. Analysis of results already available for the oxygen yield shows that oxygen originated from the radiolysis of water with a g value of approximately 0.1 (g values are derived values for yields of primary species for 100 electron volts). This finding gives material balance and provides evidence of oxygen being a product of water radiolysis.