Innospec (IOSP) could be a solid choice for investors given the company's remarkably improving earnings outlook. While the stock has been a strong performer lately, this trend might continue since analysts are still raising their earnings estimates for the company.The rising trend in estimate revisions, which is a result of growing analyst optimism on the earnings prospects of this specialty chemicals company, should get reflected in its stock price. After all, empirical research shows a strong correlation between trends in earnings estimate revisions and near-term stock price movements. This insight is at the core of our stock rating tool -- the Zacks Rank.The five-grade Zacks Rank system, which ranges from a Zacks Rank #1 (Strong Buy) to a Zacks Rank #5 (Strong Sell), has an impressive externally-audited track record of outperformance, with Zacks #1 Ranked stocks generating an average annual return of +25% since 2008.Consensus earnings estimates for the next quarter and full year have moved considerably higher for Innospec, as there has been strong agreement among the covering analysts in raising estimates.Current-Quarter Estimate RevisionsFor the current quarter, the company is expected to earn $1.41 per share, which is a change of +22.61% from the year-ago reported number.Over the last 30 days, two estimates have moved higher for Innospec compared to no negative revisions. As a result, the Zacks Consensus Estimate has increased 19.07%.Current-Year Estimate RevisionsFor the full year, the earnings estimate of $5.95 per share represents a change of +23.96% from the year-ago number.In terms of estimate revisions, the trend for the current year also appears quite encouraging for Innospec. Over the past month, two estimates have moved higher compared to no negative revisions, helping the consensus estimate increase 6.35%.Favorable Zacks RankThe promising estimate revisions have helped Innospec earn a Zacks Rank #1 (Strong Buy). The Zacks Rank is a tried-and-tested rating tool that helps investors effectively harness the power of earnings estimate revisions and make the right investment decision. You can see the complete list of today's Zacks #1 Rank (Strong Buy) stocks here.Our research shows that stocks with Zacks Rank #1 (Strong Buy) and 2 (Buy) significantly outperform the S&P 500.Bottom LineInnospec shares have added 7.7% over the past four weeks, suggesting that investors are betting on its impressive estimate revisions. So, you may consider adding it to your portfolio right away to benefit from its earnings growth prospects. Zacks' Top Picks to Cash in on Electric Vehicles Big money has already been made in the Electric Vehicle (EV) industry. But, the EV revolution has not hit full throttle yet. There is a lot of money to be made as the next push for future technologies ramps up. Zacks’ Special Report reveals 5 picks investorsSee 5 EV Stocks With Extreme Upside Potential >>Want the latest recommendations from Zacks Investment Research? Today, you can download 7 Best Stocks for the Next 30 Days. Click to get this free report Innospec Inc. (IOSP): Free Stock Analysis Report To read this article on Zacks.com click here.