how do I make the records output through Data::Dumper come out as "Particípio Passado" instead of "Partic\x{c3}\x{ad}pio Passado"?

The string isn't "Particípio Passado"; it's the UTF-8 encoding of "Particípio Passado". If you had "Particípio Passado", Data::Dumper would print one of the following (depending on a couple of factors):

$VAR1 = "Particípio Passado";
$VAR1 = "Partic\x{ed}pio Passado";
$VAR1 = "Partic\355pio Passado";
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(The first would only show up correctly if you properly encode your output. We'll get back to that.)

If you're using JSON::XS, this problem would arise if you didn't call ->utf8.

my $json_parser = JSON::XS->new->utf8;
my $data = $json_parser->decode($json_string);
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If I do a normal print of the keys, they come right

Given that the string is wrong, that indicates there are other problems. (i.e. Two wrongs made a right.)

First, I bet your Perl source file is encoded using UTF-8, but you didn't tell Perl that using

use utf8;
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Secondly, I bet you have a UTF-8 terminal, but you didn't tell Perl that using one of

use open ':std', 'locale';
use open ':std', ':encoding(UTF-8)';
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