We　report　a　novel　humidity　sensor　featuring　vertically　oriented　arrays　of　ReS2　nanosheets　grown　on　an　interdigitated　gold　electrode　by　chemical　vapor　deposition.　The　vertical　orientation　of　the　nanosheets　is　important　since　it　maximizes　the　exposed　surface　area　for　water　adsorption/desorption.　We　find　that　the　resistance　of　the　ReS2　film　decreases　sensitively　with　increasing　relative　humidity,　which　we　attribute　to　charge　transfer　from　the　absorbed　H2O　molecules　to　the　n-doped　ReS2　nanosheets.　In　addition　to　high　sensitivity,　the　ReS2　sensors　exhibit　fast　response/recovery　time　and　excellent　reversibility　with　minimal　hysteresis.　Moreover,　our　fabrication　approach　involving　the　direct　(　1-step)　growth　of　the　ReS2　films　on　an　interdigitated　electrode　(　without　any　transfer　using　wet　chemistry　or　lithography)　greatly　simplifies　the　device　architecture　and　has　important　practical　benefits　for　the　low-cost　and　scalable　deployment　of　such　sensor　devices.