[Solved]-Plot time on Y-axis and users on X-axis Highcharts-Highcharts

If you want the Datetime format, you need to assign dates too. There is nothing such as a time format.

For that you can assign a date for your times and edit the options to show only the hours and minutes.

You can do something like this:

http://jsfiddle.net/pqyj7o0q/1/

by adding:

type: 'datetime'
min: Date.UTC(Year, month, day),
max: Date.UTC(Year, month, day)

to your yAxis and also changing your data to date formats like above.