: You will have to URL encode the string correctly and supply date in format : Solr expects. Please check this: http://wiki.apache.org/solr/SolrQuerySyntax
beyond that, you may also need to worry about lucene query sytnax escaping ...the query parser can see the ":" character and think you are searching for "mm:ss" in the field "yyyy-mm-ddThh" this isn't something people typically need to worry about when range searching on dates (becuase query parser doesn't treat ":" as special in a range query) but if you are are looking for exact date matches you'll probably want to quote the date value... date_field:"2009-01-09T00:00:00Z" -Hoss