diff --git a/include/HDF_IO.hh b/include/HDF_IO.hh
index 1b15b34..a8a50b6 100755
--- a/include/HDF_IO.hh
+++ b/include/HDF_IO.hh
@@ -886,6 +886,60 @@ inline void HDFWriteDatasetVector( const std::string Filename, const std::string
   H5Fclose( HDF_FileID );
 }
 
+template< typename T >
+inline void HDFCreateEmptyDataset( const std::string Filename, const std::string ObjName, const size_t num_particles)
+{
+
+  hid_t
+    HDF_FileID,
+    HDF_DatasetID,
+    HDF_DataspaceID,
+    HDF_Type;
+
+  hsize_t HDF_Dims;
+
+  HDF_FileID = H5Fopen( Filename.c_str(), H5F_ACC_RDWR, H5P_DEFAULT );
+
+  HDF_Type                = GetDataType<T>();
+
+  HDF_Dims                = (hsize_t) (num_particles);
+  HDF_DataspaceID         = H5Screate_simple(1, &HDF_Dims, NULL);
+  HDF_DatasetID           = H5Dcreate( HDF_FileID, ObjName.c_str(), HDF_Type,
+                                       HDF_DataspaceID, H5P_DEFAULT );
+  H5Dclose( HDF_DatasetID );
+  H5Sclose( HDF_DataspaceID );
+
+  H5Fclose( HDF_FileID );
+}
+
+template< typename T >
+inline void HDFCreateEmptyDatasetVector( const std::string Filename, const std::string ObjName, const size_t num_particles)
+{
+
+    hid_t
+    HDF_FileID,
+    HDF_DatasetID,
+    HDF_DataspaceID,
+    HDF_Type;
+
+  hsize_t HDF_Dims[2];
+
+  HDF_FileID = H5Fopen( Filename.c_str(), H5F_ACC_RDWR, H5P_DEFAULT );
+
+  HDF_Type                = GetDataType<T>();
+
+  HDF_Dims[0]             = (hsize_t) (num_particles);
+  HDF_Dims[1]             = (hsize_t) 3;
+  
+  HDF_DataspaceID         = H5Screate_simple(2, HDF_Dims, NULL);
+  HDF_DatasetID           = H5Dcreate( HDF_FileID, ObjName.c_str(), HDF_Type,
+                                       HDF_DataspaceID, H5P_DEFAULT );
+  H5Dclose( HDF_DatasetID );
+  H5Sclose( HDF_DataspaceID );
+  H5Fclose( HDF_FileID );
+  
+}
+
 inline void HDFCreateGroup( const std::string Filename, const std::string GroupName )
 {
 	hid_t HDF_FileID, HDF_GroupID;
diff --git a/src/plugins/output_swift.cc b/src/plugins/output_swift.cc
index ab32d6a..06e85c8 100644
--- a/src/plugins/output_swift.cc
+++ b/src/plugins/output_swift.cc
@@ -60,7 +60,7 @@ public:
     // SWIFT uses a single file as IC */
     num_files_ = 1;
     this_rank_ = 0;
-    num_files_ = 1;
+    num_ranks_ = 1;
 
     real_t astart = 1.0 / (1.0 + cf_.get_value<double>("setup", "zstart"));
     const double rhoc = 27.7519737; // in h^2 1e10 M_sol / Mpc^3
@@ -251,7 +251,45 @@ public:
     else
       mass_[sid] = Omega_species * munit_ / pc.get_global_num_particles();
 
-    HDFCreateGroup(fname_, std::string("PartType") + std::to_string(sid));
+    const size_t global_num_particles =  pc.get_global_num_particles();
+    
+    // start by creating the full empty datasets in the file
+    if (this_rank_ == 0) {
+
+      HDFCreateGroup(fname_, std::string("PartType") + std::to_string(sid));
+
+      if (this->has_64bit_reals())
+      {
+	HDFCreateEmptyDatasetVector<double>(fname_, std::string("PartType") + std::to_string(sid) + std::string("/Coordinates"), global_num_particles);
+	HDFCreateEmptyDatasetVector<double>(fname_, std::string("PartType") + std::to_string(sid) + std::string("/Velocities"), global_num_particles);
+      }
+      else
+      {
+	HDFCreateEmptyDatasetVector<float>(fname_, std::string("PartType") + std::to_string(sid) + std::string("/Coordinates"), global_num_particles);
+	HDFCreateEmptyDatasetVector<float>(fname_, std::string("PartType") + std::to_string(sid) + std::string("/Velocities"), global_num_particles);
+      }
+
+      if (this->has_64bit_ids())
+	HDFCreateEmptyDataset<uint64_t>(fname_, std::string("PartType") + std::to_string(sid) + std::string("/ParticleIDs"), global_num_particles);
+      else
+	HDFCreateEmptyDataset<uint32_t>(fname_, std::string("PartType") + std::to_string(sid) + std::string("/ParticleIDs"), global_num_particles);
+
+      if( pc.bhas_individual_masses_ ){
+	if (this->has_64bit_reals())
+	  HDFCreateEmptyDataset<double>(fname_, std::string("PartType") + std::to_string(sid) + std::string("/Masses"), global_num_particles);
+	else 
+	  HDFCreateEmptyDataset<float>(fname_, std::string("PartType") + std::to_string(sid) + std::string("/Masses"), global_num_particles);      
+      }
+
+      if( bdobaryons_ && s == cosmo_species::baryon) {
+
+	// note: despite this being a constant array we still need to handle it in a distributed way
+	HDFCreateEmptyDataset<write_real_t>(fname_, std::string("PartType") + std::to_string(sid) + std::string("/InternalEnergy"), global_num_particles);
+	HDFCreateEmptyDataset<write_real_t>(fname_, std::string("PartType") + std::to_string(sid) + std::string("/SmoothinLength"), global_num_particles);
+      }
+    }
+
+    // Now each node writes its own chunk in a round-robin fashion, appending at the end of the currently existing data 
 
     //... write positions and velocities.....
     if (this->has_64bit_reals())