I got this input <?xml version="1.0" encoding="UTF-8"?> <result> <datapoint poiid="2492" period="2004" value="1240"/> <datapoint poiid="2492" period="2005" value="1290"/> <datapoint poiid="2492" period="2006" value="1280"/> <datapoint poiid="2492" period="2007" value="1320"/> <datapoint poiid="2492" period="2008" value="1330"/> <datapoint poiid="2492" period="2009" value="1340"/> <datapoint poiid="2492" period="2010" value="1340"/> <datapoint poiid="2492" period="2011" value="1335"/> <datapoint poiid="2493" period="2004" value="1120"/> <datapoint poiid="2493" period="2005" value="1120"/> <datapoint poiid="2493" period="2006" value="1100"/> <datapoint poiid="2493" period="2007" value="1100"/> <datapoint poiid="2493" period="2008" value="1100"/> <datapoint poiid="2493" period="2009" value="1110"/> <datapoint poiid="2493" period="2010" value="1105"/> <datapoint poiid="2493" period="2011" value="1105"/> </result> and I use this xslt 2.0 <?xml version="1.0" encoding="UTF-8"?> <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:xs="http://www.w3.org/2001/XMLSchema" exclude-result-prefixes="xs" version="2.0"> <xsl:output method="xml" indent="yes"/> <xsl:template match="result"> <xsl:for-each-group select="datapoint" group-by="@poiid"> <node type="poiid" id="{@poiid}"> <xsl:for-each select="current-group()"> <node type="period" id="{@period}" value="{@value}"/> </xsl:for-each> </node> </xsl:for-each-group> </xsl:template> </xsl:stylesheet> to convert it into <?xml version="1.0" encoding="UTF-8"?> <node type="poiid" id="2492"> <node type="period" id="2004" value="1240"/> <node type="period" id="2005" value="1290"/> <node type="period" id="2006" value="1280"/> <node type="period" id="2007" value="1320"/> <node type="period" id="2008" value="1330"/> <node type="period" id="2009" value="1340"/> <node type="period" id="2010" value="1340"/> <node type="period" id="2011" value="1335"/> </node> <node type="poiid" id="2493"> <node type="period" id="2004" value="1120"/> <node type="period" id="2005" value="1120"/> <node type="period" id="2006" value="1100"/> <node type="period" id="2007" value="1100"/> <node type="period" id="2008" value="1100"/> <node type="period" id="2009" value="1110"/> <node type="period" id="2010" value="1105"/> <node type="period" id="2011" value="1105"/> </node> Works smoothly. Where I got stuck is when I tried to make it more dynamic. The real life input has 6 attributes for each datapoint instead of 3, and the usecase requires the possibility to set the grouping parameters dynamically. I tried using parameters <xsl:param name="k1" select="'poiid'"/> <xsl:param name="k2" select="'period'"/> but passing them to the rest of the xslt is something that I can't get right. The code below doesn't work, but clarifies hopefully, what I'm looking for. <xsl:template match="result"> <xsl:for-each-group select="datapoint" group-by="@{$k1}"> <node type="{$k1}" id="@{$k1}"> <xsl:for-each select="current-group()"> <node type="{$k2}" id="@{$k2}" value="{@value}"/> </xsl:for-each> </node> </xsl:for-each-group> </xsl:template> Any help appreciated..