The reaction of F atoms with HN3 forms the products HF (+N-3) or HNF (+N-2). The product branching fraction for this reaction has been investigated in a room-temperature flow reactor using laser-induced fluorescence to monitor the concentration of HNF. A microwave discharge applied to a dilute flow of CF4 in argon served as the F atom source. Using reactant concentrations of (0.7-3.0) x 10(12) and (1.7-20.0) x 10(12) molecules cm(-3) for CF4 and HN3, respectively, the rate constant for formation of HNF from HN3 + F was determined to be (6.3 +/- 3.5) x 10(-12) cm(3) molecule(-1) s(-1). The average product branching fraction for formation of HNF was determined to be 0.03(-0.01)(+0.02). The quenching rate constant of electronically excited HNF by Ar was determined to be (3.0 +/- 0.3) x 10(-11) cm(3) molecule(-1) s(-1)], In addition, secondary reactions between HNF and HN3, F, and H2S were examined. No reaction was observed to occur between HNF and HN3. The reaction of HNF + F was observed to occur with an estimated rate constant of 2.0 x 10(-10) cm(3) molecule(-1) s(-1). The rate constant for the reaction between HNF and H2S was found to be less than 1 x 10(-12) cm(3) molecule(-1) s(-1).