It looks like your HTML page is encoded as UTF-8 but you are parsing as ISO-8859-1. You need to ensure you specify the correct encoding when parsing. If you are parsing from a string Nokogiri should use the same encoding as the string. If you are parsing from an IO object you can specify the encoding as the third argument to the parse
method:
Nokogiri::HTML::Document.parse(io_object, nil, 'UTF-8')