Bio Ionic Onepass Straightening Iron

Best Flat Iron to Splurge On

Why people love it
  • Seriously a onepass flat iron 
  • Great for thick and coarse hair 
  • Leaves hair looking marvelous

This professional-grade flat iron has silicon strips for ultra-smooth operation and speedy heating. The negative ion technology ensures smooth looking hair with this 1.5” flat iron.

Besides being a pricey hair straightener, you’ll need to remember to shut this off; and it only works with North American power standards.


This is a true onepass flat iron from the folks at Bio Ionic. You’ll be in and out of the bathroom in no time at all. And that all starts with the super-fast 5 second heating at startup. Yes, you read that right. Of course, if you give it another 10 seconds it will be at whatever temperature you want. Plus, it’s ceramic, so you shouldn’t expect any snags. That and the silicone strips make for a truly pleasant, cushioned experience.

Infrared technology and negative ions combine to ensure your hair remains moisturized, no matter how hot you set the temperature (it can go up to 400ºF). And, the 1.5” plates can handle a lot of hair really quickly. Though it is a bit wide for curling, you can get a few big curls out of this flat iron. You just need to remember to turn it off (sorry, no auto shut-off), but justifying the price won’t be difficult at all.


Heating speed: 5 second

Temperature and controls: Up to 400ºF with 4 different heat settings

Plates: Ceramic

Size: 1.5"

Shut-off: Manual

Voltage: American only

Price: This is a seriously expensive flat iron at $200, but users say it’s worth every penny.

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