diff --git a/php-export-data.class.php b/php-export-data.class.php
index 440e1c4..cad7434 100755
--- a/php-export-data.class.php
+++ b/php-export-data.class.php
@@ -198,7 +198,7 @@ function generateRow($row) {
 		return $output;
 	}
 	
-	private function generateCell($item) {
+	protected function generateCell($item) {
 		$output = '';
 		$style = '';
 		
@@ -211,7 +211,14 @@ private function generateCell($item) {
 		// Note we want to be very strict in what we consider a date. There is the possibility
 		// of really screwing up the data if we try to reformat a string that was not actually 
 		// intended to represent a date.
-		elseif(preg_match("/^(\d{1,2}|\d{4})[\/\-]\d{1,2}[\/\-](\d{1,2}|\d{4})([^\d].+)?$/",$item) &&
+		elseif (preg_match('_^
+				# dates: 2010-07-14 or 7/14/2010
+				(?:\d{1,2}|\d{4})[/-]\d{1,2}[/-](?:\d{1,2}|\d{4})
+				# optional time
+				(?:[T\s]+ # separated by space or T
+				[\d:,]+ # hours:minutes
+				)?
+				$_x', $item) &&
 					($timestamp = strtotime($item)) &&
 					($timestamp > 0) &&
 					($timestamp < strtotime('+500 years'))) {
@@ -237,4 +244,4 @@ function sendHttpHeaders() {
 		header("Content-Disposition: inline; filename=\"" . basename($this->filename) . "\"");
 	}
 	
-}
\ No newline at end of file
+}
diff --git a/test/ExportDataExcelTest.php b/test/ExportDataExcelTest.php
new file mode 100644
index 0000000..ed3ede6
--- /dev/null
+++ b/test/ExportDataExcelTest.php
@@ -0,0 +1,54 @@
+<?php
+require_once dirname(__FILE__) . '/../php-export-data.class.php';
+
+class ExportDataExcelWrap extends ExportDataExcel {
+	public function wrapGenerateCell($item) {
+		return $this->generateCell($item);
+	}
+}
+
+/**
+ *
+ */
+class ExportDataExcelTest extends PHPUnit_Framework_TestCase {
+	protected $output = 'browser';
+	/**
+	 * @var ExportDataExcel
+	 */
+	protected $object;
+
+	/**
+	 * Sets up the fixture
+	 */
+	protected function setUp() {
+		$this->object = new ExportDataExcelWrap($this->output);
+	}
+
+	/**
+	 * @covers ExportDataExcel::generateCell
+	 * @dataProvider dateProvider
+	 */
+	public function testDates($exp, $date) {
+		$res = $this->object->wrapGenerateCell($date);
+		$this->assertNotEmpty($res);
+		$res = trim($res);
+		$this->assertEquals($exp, $res);
+	}
+
+	public function dateProvider() {
+		return array(
+			// iso dates: https://en.wikipedia.org/wiki/ISO_8601
+			array('<Cell ss:StyleID="sDT"><Data ss:Type="DateTime">2010-01-02T00:00:00</Data></Cell>',"2010-01-02"),
+			array('<Cell ss:StyleID="sDT"><Data ss:Type="DateTime">2010-01-02T09:52:00</Data></Cell>', "2010-01-02 9:52"),
+			array('<Cell ss:StyleID="sDT"><Data ss:Type="DateTime">2010-01-02T10:00:00</Data></Cell>', "2010-01-02T10:00"),
+			array('<Cell ss:StyleID="sDT"><Data ss:Type="DateTime">2010-01-02T10:00:00</Data></Cell>', "2010-01-02T10:00:00"),
+			# microseconds not supported by strtotime
+#			array('<Cell ss:StyleID="sDT"><Data ss:Type="DateTime">2010-01-02T06:12:00</Data></Cell>', "2010-01-02T06:12:00,000"),
+#			array('<Cell ss:StyleID="sDT"><Data ss:Type="DateTime">2010-01-02T00:00:00</Data></Cell>', "2010-01-02T10:00:00,000"),
+			// US dates
+			array('<Cell ss:StyleID="sDT"><Data ss:Type="DateTime">2010-02-08T00:00:00</Data></Cell>', "02/08/2010 00:00"),
+			array('<Cell ss:StyleID="sDT"><Data ss:Type="DateTime">2010-02-08T00:00:00</Data></Cell>', "02/08/2010"),
+			array('<Cell ss:StyleID="sDT"><Data ss:Type="DateTime">2010-02-09T00:00:00</Data></Cell>', "2/9/2010"),
+		);
+	}
+}