See ?DateTimeClasses, ?strptime, and ?as.character This example from strptime should get you going: ## read in date/time info in format 'm/d/y h:m:s' dates <- c("02/27/92", "02/27/92", "01/14/92", "02/28/92", "02/01/92") times <- c("23:03:20", "22:29:56", "01:03:30", "18:21:03", "16:56:26") x <- paste(dates, times) z <- strptime(x, "%m/%d/%y %H:%M:%S") z Good luck, Andy