Recharts: Turn off background hover for bar charts

You can use the cursor prop on the <Tooltip /> to achieve what you need:

<Tooltip cursor={{fill: '#f00'}} />

Here's a working fiddle I made based on some example from their docs.

You can simply use transparent as a value for the fill property.

const {BarChart, Bar, XAxis, YAxis, CartesianGrid, Tooltip, Legend} = Recharts;
const data = [
      {name: 'Page A', uv: 4000, pv: 2400, amt: 2400},
      {name: 'Page B', uv: 3000, pv: 1398, amt: 2210},
      {name: 'Page C', uv: 2000, pv: 9800, amt: 2290},
      {name: 'Page D', uv: 2780, pv: 3908, amt: 2000},
      {name: 'Page E', uv: 1890, pv: 4800, amt: 2181},
      {name: 'Page F', uv: 2390, pv: 3800, amt: 2500},
      {name: 'Page G', uv: 3490, pv: 4300, amt: 2100},
];
const SimpleBarChart = React.createClass({
	render () {
  	return (
    	<BarChart width={600} height={300} data={data}
            margin={{top: 5, right: 30, left: 20, bottom: 5}}>
       <CartesianGrid strokeDasharray="3 3"/>
       <XAxis dataKey="name"/>
       <YAxis/>
       <Tooltip cursor={{fill: 'transparent'}}/>
       <Legend />
       <Bar dataKey="pv" fill="#8884d8" />
       <Bar dataKey="uv" fill="#82ca9d" />
      </BarChart>
    );
  }
})

ReactDOM.render(
  <SimpleBarChart />,
  document.getElementById('container')
);
body {
  margin: 0;
}

#container {
  -webkit-box-sizing: border-box;
  -moz-box-sizing: border-box;
  box-sizing: border-box;
  padding: 10px;
  width: 800px;
  height: 800px;
  background-color: #fff;
}
<script src="https://cdnjs.cloudflare.com/ajax/libs/babel-core/5.8.24/browser.js"></script>
<script src="https://npmcdn.com/[email protected]/dist/react-with-addons.min.js"></script>
<script src="https://npmcdn.com/[email protected]/dist/react-dom.min.js"></script>
<script src="https://npmcdn.com/[email protected]/prop-types.min.js"></script>
<script src="https://npmcdn.com/[email protected]/umd/Recharts.min.js"></script>

<div id="container">
  <!-- This element's contents will be replaced with your component. -->
</div>

The grey area you mentioned is called cursor. Quoting the Tooltip API docs:

If set false, no cursor will be drawn when tooltip is active.

So the answer to your question is:

<Tooltip cursor={false} />

BTW, I'm using [email protected]