Delayed　hydride　cracking,　which　is　observed　in　hydride-forming　metals,　due　to　the　precipitation　of　hydrides　near　the　crack　tip,　is　investigated　under　conditions　of　constant　temperature　and　crack　velocity,　plane　strain　and　small-scale　hydride-precipitation.　The　coupling　of　the　operating　physical　processes　of　hydrogen-diffusion,　hydride　precipitation　and　material　deformation　is　taken　into　account.　The　material　is　assumed　to　be　an　elastic　composite　made　of　hydrides　and　solid　solution,　with　properties　depending　locally　on　the　volume　fraction　of　the　hydrides.　In　the　present　analysis..　the　composite　elastic　properties　have　been　derived　by　a　generalized　self　consistent　model　for　particulate　composites.　With　respect　to　hydride-precipitation,　two　cases　have　been　considered:　(i)　precipitation　in　a　homogeneous　medium　with　elastic　properties,　equal　to　the　effective　properties　of　the　composite　and　(ii)　precipitation　in　an　inhomogeneous　medium,　where　the　expanding　hydride　has　different　elastic　properties　than　those　of　the　Surrounding　solid　solution.　The　differences　between　the　near-tip　field　distributions,　produced　by　the　two　precipitation　models,　are　relatively　small.　The　effect　of　the　hydrogen　concentration　far　from　the　crack　tip,　on　the　near-tip　field　is　also　studied.　It　is　shown　that　for　small　crack　growth　velocities,　near　the　threshold　stress　intensity　factor,　the　remote　hydrogen　concentration　weakly　affects　the　normalized　stress　distribution　in　the　hydride-precipitation　zone,　which　is　controlled　by　the　thermodynamically　required　hydrostatic　stress,　under　hydrogen　chemical　equilibrium.　However,　for　values　of　the　applied　stress　intensity　factor　and　the　crack　tip　velocity,　away　from　the　threshold　stress　intensity　factor　and　crack　arrest,　the　effect　of　remote　hydrogen　concentration　on　the　normalized　near-tip　stress　field　is　strong.　Reduction　of　the　remote　hydrogen　concentration　generally　leads　to　reduction　of　the　hydride-precipitation　zone　and　increase　of　the　near-tip　stresses.　Also　reduction　of　the　remote　hydrogen　concentration　leads　to　distributions　closer　to　those　under　hydrogen　chemical　equilibrium.　(c)　2005　Elsevier　Ltd.　All　rights　reserved.