I'd like to suggest something close to ISO 8601 format, where the date is represented as
YYYY-MM-DD and the time as
It's unambiguous (you never see anyone using
YYYY-DD-MM, it sorts correctly, and it doesn't depend on local month names.
Depending on your audience, this might be the ideal solution. But a lot of users are going to prefer a less ideal format.
If you use either
MM/DD/YYYY (US style) or
DD/MM/YYYY (UK style), clearly indicate on the page which one you're using; otherwise the date will be ambiguous 132 days of each year. But most US users will intensely dislike the UK format, and vice versa. And typical US users will dislike a 24-hour timestamp, preferring an AM or PM indicator.
"14h00" is not a common format in the US; "14:00" is much more common, and "2:00pm" is even more common.
Spelling out the month name avoids ambiguity and makes the order less important.
If practical, consider allowing the user to choose a time format.