Accepted answer

If the times that you have are static strings, you can convert them into a datetime object...

//convert 'string' times into a timestamp (milliseconds)
//so long as your string times are consistently formatted
//e.g. "0:03:00" not "3:00"
var t = Date.parse("1-1-1 " + yourTime)

...But if you can turn them into a millisecond value at all, you should be fine.

Then use normal time format for the y-axis, and format it as you like using the date label format...

var chart = new HighChart({
    yAxis: {
        type: 'datetime', //y-axis will be in milliseconds
        dateTimeLabelFormats: { //force all formats to be hour:minute:second
            second: '%H:%M:%S',
            minute: '%H:%M:%S',
            hour: '%H:%M:%S',
            day: '%H:%M:%S',
            week: '%H:%M:%S',
            month: '%H:%M:%S',
            year: '%H:%M:%S'

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