  We derive oxygen abundances for two samples of Seyfert 2 (Sy2) active
galactic nuclei (AGN) selected from the KPNO International Spectroscopic Survey
(KISS). The two samples from KISS include 17 intermediate-redshift (0.29 < z <
0.42) Sy2s detected via their [O III] lines, and 35 low-redshift (z < 0.1),
Halpha-detected Sy2s. The primary goal of this work is to explore whether the
metallicity distribution of these two samples changes with redshift. To
determine the oxygen abundances of the KISS galaxies, we use Cloudy to create a
large number of photoionization model grids by varying the temperature of the
accretion disk, the ratio of X-ray to UV continuum light, the ionization
parameter, the hydrogen density, and the metallicity of the narrow-line region
clouds. We link the results of these models to the observed [O III]/H-beta and
[N II]/H-alpha emission-line ratios of the KISS sample on the BPT diagram,
interpolating across the model grids to derive metallicity. The two redshift
samples overlap substantially in terms of derived metal abundances, but we find
that some of the intermediate-redshift Sy2 galaxies possess lower abundances
than their local universe counterparts. Our analysis provides evidence for
modest levels of chemical evolution (0.18 +/- 0.06 dex) over 3-4 Gyrs of
look-back time. We compare our results to other AGN abundance derivation
methods from the literature.
