Soil nutrients and N turnover were measured in 2 soil chronosequences on the Kilauea and Mauna Loa volcanoes. Hawaii Organic C and N accumulated rapidly in sites derived from volcanic ash and more slowly in sites derived from pahoehoe; a minimum of 22 kg N .cntdot. ha-1 .cntdot. yr-1 were added to tephra sites early in soil development. Substantial N fixation by an unknown organism or organisms is probably responsible for most of the N accumulated on ash. N turnover increased with soil age in both absolute (mg N/m2) and relative (g N/g of soil N) terms in both chronosequences. In comparison with other localities, net N mineralization potentials were extremely low in all of the sites except the 2 oldest ash sites. N availability is probably not related to most of the forms of ''ohi'' a dieback occurring in Hawaii, but low N availability is observed in sites susceptible to the dryland form of dieback which occurs early in primary succession.