A survey of 500 HR professionals within organisations of up to 250 employees found 55% raised the concern, while 43% said the group didn’t know how long to spend on a break or how often to take them.
The same number also said young people lacked awareness of when to use personal mobile phones.
And almost one in five (19%) said they were unable to find suitable candidates for work experience.
The study by curriculum-based education programme Barclays LifeSkills also surveyed young people. Of 2,000 14 to 25-year-olds, 54% said they lacked the practical skills needed to find an entry-level job.
Almost a quarter (24%) blamed a lack of careers education for their concern, while 30% said they had not received the training they needed to be successful in work.
A quarter (24%) agreed they didn’t know when to use personal mobile phones and the same proportion (25%) admitted to being unsure of appropriate personal presentation in the workplace, such as what to wear.
National Youth Agency (NYA) CEO Fiona Blacke said more needed to be done to equip young people with the skills to enter the job market.
The NYA has partnered with LifeSkills to deliver training through youth workers.
“It’s not just about getting young people into work; it’s about giving them the skills to keep them there,” Blacke said.
“Through our partnership with Barclays, delivering a financial capability project in a youth work setting, we have watched young people increase their confidence, self-esteem, leadership and communication skills as well as understand how to work together.
“We have found youth workers to be ideally placed to guide young people through the transition from school to employment.
LifeSkills head Kirstie Mackey agreed that young people needed to receive more support from schools and employers.
“We know many young people already have plenty of key skills; they just need support to understand how to put them into practice,” she said.
“We should do more to support teachers and businesses alike by providing the tools to equip young people with the employability skills they’ll need when they leave education.”
LifeSkills published the research ahead of LifeSkills National Careers Week, which will be held in more than 1,600 UK schools from 3 March 2014.