Google currently stores personal search data for 18 months
The search giant has said it will anonymise identifiable IP addresses on its server logs after nine months.
Google said respecting users' privacy is "fundamental to earning and keeping their trust".
In April, an EU advisory body recommended search engines should delete personal data within six months.
Google currently collects and stores information from each search query, holding information about the search query itself, the unique PC address (known as an IP number), and details about how a user makes their searches, such as the web browser that is being used.
The company says it needs this information to improve its various services and to help fight threats such as fraud, spam and malicious attacks, and to aid "valid legal orders" from law enforcement agencies.
It keeps this information for a set period before "anonymising" it - disconnecting the data from an individual.
In June last year, Google announced it was cutting the amount of time such data was stored from 24 to 18 months.
Google user Dan Senior quizzes the company's privacy boss, Peter Fleischer, about why it stores his details. First published on 15 Jun 2007.
The move is a response to the EU's Article 29 Working Body, a data protection advisory group that wrote to the firm questioning its privacy policies.
The group stated in a report published in April that Google had "insufficiently explained" why they were storing and processing personal data.
Peter Fleischer, Google's global privacy counsel, said in a reply to the group that the decision to further limit the amount of time to nine months was to "address regulatory concerns and to take another step to improve privacy for users".
"Finding the right balance between data retention and privacy is a tough issue for policymakers, Google and our industry." he said.
"There is great utility in data, but we also believe that limiting the amount and types of data we keep can improve privacy while continuing to provide a strong user experience."
He added that anonymising the data earlier will have costs, particularly in terms of future search quality improvements, but the company was working hard to minimise those losses.
The move by Google also follows a recent legal battle with Viacom, which had ordered the company to provide the personal details of millions of YouTube users.
Viacom has a $1bn (£497m) copyright infringement lawsuit against Google, owners of YouTube.
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