#!/usr/bin/perl

use strict;

use XML::Twig;
use Encode qw( decode );

my $twig=XML::Twig->new(pretty_print => 'indented');
   $twig->parse( '<?xml version="1.0" encoding="UTF-8"?><myxml/>'); 

my $root= $twig->root;  

$root->set_att( 'fille' => decode('UTF-8', 'clémence') );

open(PF, ">", "out.xml") or die "can't open file $!\n";

$twig->print(\*PF);