diff --git a/lib/eclipse/EclipseState/Eclipse3DProperties.cpp b/lib/eclipse/EclipseState/Eclipse3DProperties.cpp
index 4e1d60b33..54b5e5e48 100644
--- a/lib/eclipse/EclipseState/Eclipse3DProperties.cpp
+++ b/lib/eclipse/EclipseState/Eclipse3DProperties.cpp
@@ -395,6 +395,9 @@ namespace Opm {
         for( const auto& kw : { "PERMXY", "PERMYZ", "PERMZX" } )
             supportedDoubleKeywords.emplace_back( kw, nan, distributeTopLayer, "Permeability" );
 
+        /* A pure OPM keyword */
+        supportedDoubleKeywords.emplace_back( "RHO", nan, "Density" );
+
         /* the transmissibility keywords for neighboring connections. note that
          * these keywords don't seem to require a post-processor
          */
diff --git a/lib/eclipse/share/keywords/900_OPM/R/RHO b/lib/eclipse/share/keywords/900_OPM/R/RHO
new file mode 100644
index 000000000..d8259e9ed
--- /dev/null
+++ b/lib/eclipse/share/keywords/900_OPM/R/RHO
@@ -0,0 +1,2 @@
+{"name" : "RHO" , "sections" : ["GRID"], "data" : {"value_type" : "DOUBLE" , "default" : 0 , "dimension":"Density"}}
+
diff --git a/lib/eclipse/share/keywords/keyword_list.cmake b/lib/eclipse/share/keywords/keyword_list.cmake
index 36087158a..82cf198fc 100644
--- a/lib/eclipse/share/keywords/keyword_list.cmake
+++ b/lib/eclipse/share/keywords/keyword_list.cmake
@@ -385,5 +385,6 @@ set( keywords
      900_OPM/G/GRUPRIG
      900_OPM/M/MINPVFIL
      900_OPM/O/OCOMPIDX
+     900_OPM/R/RHO
      900_OPM/T/TLPMIXPA)
-       
+