Hi Nhan, Are you trying to convert a CDM-compliant dataset (i.e. a dataset that NJ can understand) into NetCDF-4? If that's it, we have a command-line interface for that operation [1]. You may not need to do any programming at all! Otherwise, you can find some hints in FileWriter2. This line [2] in particular deals with adding a structure variable. If you send me your input file and example code, I can take a shot at it, if you like. Cheers, Christian [1] http://www.unidata.ucar.edu/software/thredds/current/netcdf-java/reference/manPages.html#nccopy [2] https://github.com/Unidata/thredds/blob/4.5.4/cdm/src/main/java/ucar/nc2/FileWriter2.java#L328 Ticket Details =================== Ticket ID: RWH-394641 Department: Support netCDF Java Priority: Low Status: Closed