my $result = 'Pass';
my %ParamGroup = ( ParameterGroupID => '1' );

my $ns     = '...';
my $schema = '...';
my $xsi_ns = 'http://www.w3.org/2001/XMLSchema-instance';

my $doc = XML::LibXML::Document->new('1.0', 'utf-8'); 

my $root = $doc->createElementNS($ns, "TestResult");
$root->setAttributeNS($xsi_ns, 'xsi:schemaLocation' => $schema);

{
   my $result_node = $doc->createElement('result');
   $result_node->appendTextNode($result);

   $root->appendChild($result_node);
}

{
   my $params_node = $doc->createElement("Parameters");

   for my $param_group (keys %ParamGroup) {
      my $param_group_node = $doc->createElement($param_group);
      $param_group_node->appendTextNode($ParamGroup{$param_group});
      $params_node->appendChild($param_group_node);
   }

   $root->appendChild($params_node);
}

$doc->setDocumentElement($root);
[download]

Thanks ikegami... I get an output like

<Parameters>
    <ParameterGroupID>1</ParameterGroupID>
  </Parameters>
[download]

if I want to add nodes like this..how should I use set attribute ?

<Parameters>
<ParameterGroup ID="Group1">
 <Parameter key="Key1">Some Value</Parameter> 
 <Parameter key="Key2">Some Value</Parameter> 
 <Parameter key="Key3">Some Value</Parameter> 
 </ParameterGroup>
</Parameters>
[download]

Thanks a lot

You've already shown you know how to create nodes, give them attributes, and add children to them. What's the problem? And like I asked on SO, what have you tried? I can't point out your error if you don't show your code.