my %hash1 = (
700200 => '523235',
700204 => '523221',
);

my %hash2 = (
523235 => 'Title1',
523221 => 'Title2',
);

##</code><code>##

my $value1;
foreach my $key1 (keys(%hash1)) {
  $value1 = $hash1{key1};
  foreach my $key2 (keys (%hash2)) {
    if ($value1 eq $key2){
	$hash3{$key1}= $hash2{$key2};
   }
  }
 }

print Dumper \%hash3;

#this should be the expected result
$VAR1 = {
700200 => 'Title1',
700204 => 'Title2',
};